Hướng dẫn dùng caseconvert JavaScript

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Is there a simple way to convert a string to Title Case? E.g. john smith becomes John Smith. I'm not looking for something complicated like John Resig's solution, just (hopefully) some kind of one- or two-liner.

Penny Liu

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asked Oct 13, 2008 at 8:05

5

Try this:

function toTitleCase(str) {
  return str.replace(
    /\w\S*/g,
    function(txt) {
      return txt.charAt(0).toUpperCase() + txt.substr(1).toLowerCase();
    }
  );
}

  Input:
  

  
Output:
  

meyi

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answered Oct 13, 2008 at 8:18

Greg DeanGreg Dean

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19

If a CSS solution meets your needs, you can apply the text-transform CSS style to your controls:

text-transform: capitalize;

Just be aware that this will transform:
hello world to Hello World
HELLO WORLD to HELLO WORLD (no change)
emily-jane o'brien to Emily-jane O'brien (incorrect)
Maria von Trapp to Maria Von Trapp (incorrect)

Michael

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answered Jun 16, 2010 at 14:58

Talha AshfaqueTalha Ashfaque

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13

A slightly more elegant way, adapting Greg Dean's function:

String.prototype.toProperCase = function () {
    return this.replace(/\w\S*/g, function(txt){return txt.charAt(0).toUpperCase() + txt.substr(1).toLowerCase();});
};

Call it like:

"pascal".toProperCase();

answered Apr 7, 2011 at 0:14

TuanTuan

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8

Here's my version, IMO it's easy to understand and elegant too.

const str = "foo bar baz";
const newStr = str.split(' ')
   .map(w => w[0].toUpperCase() + w.substring(1).toLowerCase())
   .join(' ');
console.log(newStr);

xinthose

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answered Mar 5, 2014 at 9:07

a8ma8m

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Here’s my function that converts to title case but also preserves defined acronyms as uppercase and minor words as lowercase:

String.prototype.toTitleCase = function() {
  var i, j, str, lowers, uppers;
  str = this.replace(/([^\W_]+[^\s-]*) */g, function(txt) {
    return txt.charAt(0).toUpperCase() + txt.substr(1).toLowerCase();
  });

  // Certain minor words should be left lowercase unless 
  // they are the first or last words in the string
  lowers = ['A', 'An', 'The', 'And', 'But', 'Or', 'For', 'Nor', 'As', 'At', 
  'By', 'For', 'From', 'In', 'Into', 'Near', 'Of', 'On', 'Onto', 'To', 'With'];
  for (i = 0, j = lowers.length; i < j; i++)
    str = str.replace(new RegExp('\\s' + lowers[i] + '\\s', 'g'), 
      function(txt) {
        return txt.toLowerCase();
      });

  // Certain words such as initialisms or acronyms should be left uppercase
  uppers = ['Id', 'Tv'];
  for (i = 0, j = uppers.length; i < j; i++)
    str = str.replace(new RegExp('\\b' + uppers[i] + '\\b', 'g'), 
      uppers[i].toUpperCase());

  return str;
}

For example:

"TO LOGIN TO THIS SITE and watch tv, please enter a valid id:".toTitleCase();
// Returns: "To Login to This Site and Watch TV, Please Enter a Valid ID:"

answered Jun 25, 2011 at 1:04

Geoffrey BoothGeoffrey Booth

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10

I prefer the following over the other answers. It matches only the first letter of each word and capitalises it. Simpler code, easier to read and less bytes. It preserves existing capital letters to prevent distorting acronyms. However you can always call toLowerCase() on your string first.

function title(str) {
  return str.replace(/(^|\s)\S/g, function(t) { return t.toUpperCase() });
}

You can add this to your string prototype which will allow you to 'my string'.toTitle() as follows:

String.prototype.toTitle = function() {
  return this.replace(/(^|\s)\S/g, function(t) { return t.toUpperCase() });
}

Example:

answered Oct 26, 2017 at 16:36

Tom KayTom Kay

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You could immediately toLowerCase the string, and then just toUpperCase the first letter of each word. Becomes a very simple 1 liner:

function titleCase(str) {
  return str.toLowerCase().replace(/\b\w/g, s => s.toUpperCase());
}

console.log(titleCase('iron man'));
console.log(titleCase('iNcrEdible hulK'));

answered Oct 18, 2016 at 15:09

KevBotKevBot

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6

Benchmark

TL;DR

The winner of this benchmark is the plain old for loop:

function titleize(str) {
    let upper = true
    let newStr = ""
    for (let i = 0, l = str.length; i < l; i++) {
        // Note that you can also check for all kinds of spaces  with
        // str[i].match(/\s/)
        if (str[i] == " ") {
            upper = true
            newStr += str[i]
            continue
        }
        newStr += upper ? str[i].toUpperCase() : str[i].toLowerCase()
        upper = false
    }
    return newStr
}
// NOTE: you could beat that using charcode and string builder I guess.

Details

I've taken the most popular and distinct answers and made a benchmark with those.

Here's the result on my MacBook pro:

And for completeness, here are the functions used:

str = "the QUICK BrOWn Fox jUMPS oVeR the LAzy doG";
function regex(str) {
  return str.replace(
    /\w\S*/g,
    function(txt) {
      return txt.charAt(0).toUpperCase() + txt.substr(1).toLowerCase();
    }
  );
}

function split(str) {
  return str.
    split(' ').
    map(w => w[0].toUpperCase() + w.substr(1).toLowerCase()).
    join(' ');
}

function complete(str) {
  var i, j, str, lowers, uppers;
  str = str.replace(/([^\W_]+[^\s-]*) */g, function(txt) {
    return txt.charAt(0).toUpperCase() + txt.substr(1).toLowerCase();
  });

  // Certain minor words should be left lowercase unless 
  // they are the first or last words in the string
  lowers = ['A', 'An', 'The', 'And', 'But', 'Or', 'For', 'Nor', 'As', 'At', 
  'By', 'For', 'From', 'In', 'Into', 'Near', 'Of', 'On', 'Onto', 'To', 'With'];
  for (i = 0, j = lowers.length; i < j; i++)
    str = str.replace(new RegExp('\\s' + lowers[i] + '\\s', 'g'), 
      function(txt) {
        return txt.toLowerCase();
      });

  // Certain words such as initialisms or acronyms should be left uppercase
  uppers = ['Id', 'Tv'];
  for (i = 0, j = uppers.length; i < j; i++)
    str = str.replace(new RegExp('\\b' + uppers[i] + '\\b', 'g'), 
      uppers[i].toUpperCase());

  return str;
}

function firstLetterOnly(str) {
  return str.replace(/\b(\S)/g, function(t) { return t.toUpperCase(); });
}

function forLoop(str) {
  let upper = true;
  let newStr = "";
  for (let i = 0, l = str.length; i < l; i++) {
    if (str[i] == " ") {
      upper = true;
        newStr += " ";
      continue;
    }
    newStr += upper ? str[i].toUpperCase() : str[i].toLowerCase();
    upper = false;
  }
  return newStr;
}

Note that i deliberately did not change the prototype since I consider it a really bad practice and I don't think we should promote such practice in our answers. This is only ok for small codebases when you're the only one working on it.

If you want to add any other way to do it to this benchmark, please comment a link to the answer !

EDIT 2022 Mac M1: On my new computer, with more recent chrome, split wins. If you really care about performance on a specific machine you should run the benchmark yourself

answered Nov 19, 2020 at 10:56

Ulysse BNUlysse BN

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4

var result =
  'this is very interesting'.replace(/\b[a-z]/g, (x) => x.toUpperCase())

console.log(result) // This Is Very Interesting

answered Dec 24, 2013 at 15:17

simosimo

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5

Surprised to see no one mentioned the use of rest parameter. Here is a simple one liner that uses ES6 Rest parameters.

let str="john smith"
str=str.split(" ").map(([firstChar,...rest])=>firstChar.toUpperCase()+rest.join("").toLowerCase()).join(" ")
console.log(str)

answered May 18, 2020 at 16:53

kapil pandeykapil pandey

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0

Without using regex just for reference:

String.prototype.toProperCase = function() {
  var words = this.split(' ');
  var results = [];
  for (var i = 0; i < words.length; i++) {
    var letter = words[i].charAt(0).toUpperCase();
    results.push(letter + words[i].slice(1));
  }
  return results.join(' ');
};

console.log(
  'john smith'.toProperCase()
)

adiga

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answered Dec 19, 2011 at 16:25

MikeMike

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1

Just in case you are worried about those filler words, you can always just tell the function what not to capitalize.

/**
 * @param String str The text to be converted to titleCase.
 * @param Array glue the words to leave in lowercase. 
 */
var titleCase = function(str, glue){
    glue = (glue) ? glue : ['of', 'for', 'and'];
    return str.replace(/(\w)(\w*)/g, function(_, i, r){
        var j = i.toUpperCase() + (r != null ? r : "");
        return (glue.indexOf(j.toLowerCase())<0)?j:j.toLowerCase();
    });
};

Hope this helps you out.

edit

If you want to handle leading glue words, you can keep track of this w/ one more variable:

var titleCase = function(str, glue){
    glue = !!glue ? glue : ['of', 'for', 'and', 'a'];
    var first = true;
    return str.replace(/(\w)(\w*)/g, function(_, i, r) {
        var j = i.toUpperCase() + (r != null ? r : '').toLowerCase();
        var result = ((glue.indexOf(j.toLowerCase()) < 0) || first) ? j : j.toLowerCase();
        first = false;
        return result;
    });
};

answered Nov 13, 2010 at 5:17

fncompfncomp

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6

If you need a grammatically correct answer:

This answer takes into account prepositions such as "of", "from", .. The output will generate an editorial style title you would expect to see in a paper.

toTitleCase Function

The function that takes into account grammar rules listed here. The function also consolidates whitespace and removes special characters (modify regex for your needs)

const toTitleCase = (str) => {
  const articles = ['a', 'an', 'the'];
  const conjunctions = ['for', 'and', 'nor', 'but', 'or', 'yet', 'so'];
  const prepositions = [
    'with', 'at', 'from', 'into','upon', 'of', 'to', 'in', 'for',
    'on', 'by', 'like', 'over', 'plus', 'but', 'up', 'down', 'off', 'near'
  ];

  // The list of spacial characters can be tweaked here
  const replaceCharsWithSpace = (str) => str.replace(/[^0-9a-z&/\\]/gi, ' ').replace(/(\s\s+)/gi, ' ');
  const capitalizeFirstLetter = (str) => str.charAt(0).toUpperCase() + str.substr(1);
  const normalizeStr = (str) => str.toLowerCase().trim();
  const shouldCapitalize = (word, fullWordList, posWithinStr) => {
    if ((posWithinStr == 0) || (posWithinStr == fullWordList.length - 1)) {
      return true;
    }

    return !(articles.includes(word) || conjunctions.includes(word) || prepositions.includes(word));
  }

  str = replaceCharsWithSpace(str);
  str = normalizeStr(str);

  let words = str.split(' ');
  if (words.length <= 2) { // Strings less than 3 words long should always have first words capitalized
    words = words.map(w => capitalizeFirstLetter(w));
  }
  else {
    for (let i = 0; i < words.length; i++) {
      words[i] = (shouldCapitalize(words[i], words, i) ? capitalizeFirstLetter(words[i], words, i) : words[i]);
    }
  }

  return words.join(' ');
}

Unit Tests to Ensure Correctness

import { expect } from 'chai';
import { toTitleCase } from '../../src/lib/stringHelper';

describe('toTitleCase', () => {
  it('Capitalizes first letter of each word irrespective of articles, conjunctions or prepositions if string is no greater than two words long', function(){
    expect(toTitleCase('the dog')).to.equal('The Dog'); // Capitalize articles when only two words long
    expect(toTitleCase('for all')).to.equal('For All'); // Capitalize conjunctions when only two words long
    expect(toTitleCase('with cats')).to.equal('With Cats'); // Capitalize prepositions when only two words long
  });

  it('Always capitalize first and last words in a string irrespective of articles, conjunctions or prepositions', function(){
    expect(toTitleCase('the beautiful dog')).to.equal('The Beautiful Dog');
    expect(toTitleCase('for all the deadly ninjas, be it so')).to.equal('For All the Deadly Ninjas Be It So');
    expect(toTitleCase('with cats and dogs we are near')).to.equal('With Cats and Dogs We Are Near');
  });

  it('Replace special characters with space', function(){
    expect(toTitleCase('[wolves & lions]: be careful')).to.equal('Wolves & Lions Be Careful');
    expect(toTitleCase('wolves & lions, be careful')).to.equal('Wolves & Lions Be Careful');
  });

  it('Trim whitespace at beginning and end', function(){
    expect(toTitleCase(' mario & Luigi superstar saga ')).to.equal('Mario & Luigi Superstar Saga');
  });

  it('articles, conjunctions and prepositions should not be capitalized in strings of 3+ words', function(){
    expect(toTitleCase('The wolf and the lion: a tale of two like animals')).to.equal('The Wolf and the Lion a Tale of Two like Animals');
    expect(toTitleCase('the  three Musketeers  And plus ')).to.equal('The Three Musketeers and Plus');
  });
});

Please note that I am removing quite a bit of special characters from the strings provided. You will need to tweak the regex to address the requirements of your project.

answered Oct 16, 2017 at 16:17

dipole_momentdipole_moment

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4

If regex used in the above solutions is getting you confused, try this code:

function titleCase(str) {
  return str.split(' ').map(function(val){ 
    return val.charAt(0).toUpperCase() + val.substr(1).toLowerCase();
  }).join(' ');
}

answered Feb 28, 2016 at 10:16

6

I made this function which can handle last names (so it's not title case) such as "McDonald" or "MacDonald" or "O'Toole" or "D'Orazio". It doesn't however handle German or Dutch names with "van" or "von" which are often in lower-case... I believe "de" is often lower-case too such as "Robert de Niro". These would still have to be addressed.

function toProperCase(s)
{
  return s.toLowerCase().replace( /\b((m)(a?c))?(\w)/g,
          function($1, $2, $3, $4, $5) { if($2){return $3.toUpperCase()+$4+$5.toUpperCase();} return $1.toUpperCase(); });
}

answered Feb 3, 2010 at 22:22

LwangamanLwangaman

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3

If you can use third party libraries in your code then lodash has a helper function for us.

https://lodash.com/docs/4.17.3#startCase

_.startCase('foo bar');
// => 'Foo Bar'

_.startCase('--foo-bar--');
// => 'Foo Bar'
 
_.startCase('fooBar');
// => 'Foo Bar'
 
_.startCase('__FOO_BAR__');
// => 'FOO BAR'

answered Dec 29, 2016 at 11:27

waqaswaqas

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ES 6

str.split(' ')
   .map(s => s.slice(0, 1).toUpperCase() + s.slice(1).toLowerCase())
   .join(' ')

else

str.split(' ').map(function (s) {
    return s.slice(0, 1).toUpperCase() + s.slice(1).toLowerCase();
}).join(' ')

Steve Bennett

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answered Oct 27, 2016 at 15:52

jssridharjssridhar

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5

First, convert your string into array by splitting it by spaces:

var words = str.split(' ');

Then use array.map to create a new array containing the capitalized words.

var capitalized = words.map(function(word) {
    return word.charAt(0).toUpperCase() + word.substring(1, word.length);
});

Then join the new array with spaces:

capitalized.join(" ");

NOTE:

This of course has a drawback. This will only capitalize the first letter of every word. By word, this means that it treats every string separated by spaces as 1 word.

Supposedly you have:

str = "I'm a little/small tea pot";

This will produce

I'm A Little/small Tea Pot

compared to the expected

I'm A Little/Small Tea Pot

In that case, using Regex and .replace will do the trick:

with ES6:

const capitalize = str => str.length
  ? str[0].toUpperCase() +
    str.slice(1).toLowerCase()
  : '';

const escape = str => str.replace(/./g, c => `\\${c}`);
const titleCase = (sentence, seps = ' _-/') => {
  let wordPattern = new RegExp(`[^${escape(seps)}]+`, 'g');
  
  return sentence.replace(wordPattern, capitalize);
};
console.log( titleCase("I'm a little/small tea pot.") );

or without ES6:

function capitalize(str) {
  return str.charAt(0).toUpperCase() + str.substring(1, str.length).toLowerCase();
}

function titleCase(str) {
  return str.replace(/[^\ \/\-\_]+/g, capitalize);
}

console.log(titleCase("I'm a little/small tea pot."));

answered Sep 30, 2017 at 9:28

xGeoxGeo

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Most of these answers seem to ignore the possibility of using the word boundary metacharacter (\b). A shorter version of Greg Dean's answer utilizing it:

function toTitleCase(str)
{
    return str.replace(/\b\w/g, function (txt) { return txt.toUpperCase(); });
}

Works for hyphenated names like Jim-Bob too.

answered Jul 16, 2014 at 14:59

lewax00lewax00

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3

var toMatch = "john w. smith";
var result = toMatch.replace(/(\w)(\w*)/g, function (_, i, r) {
      return i.toUpperCase() + (r != null ? r : "");
    }
)

Seems to work... Tested with the above, "the quick-brown, fox? /jumps/ ^over^ the ¡lazy! dog..." and "C:/program files/some vendor/their 2nd application/a file1.txt".

If you want 2Nd instead of 2nd, you can change to /([a-z])(\w*)/g.

The first form can be simplified as:

function toTitleCase(toTransform) {
  return toTransform.replace(/\b([a-z])/g, function (_, initial) {
      return initial.toUpperCase();
  });
}

answered Oct 13, 2008 at 8:17

PhiLhoPhiLho

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Try this, shortest way:

str.replace(/(^[a-z])|(\s+[a-z])/g, txt => txt.toUpperCase());

Mr. Polywhirl

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answered Jun 6, 2017 at 9:52

VikramVikram

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1

Try this

String.prototype.toProperCase = function(){
    return this.toLowerCase().replace(/(^[a-z]| [a-z]|-[a-z])/g, 
        function($1){
            return $1.toUpperCase();
        }
    );
};

Example

var str = 'john smith';
str.toProperCase();

answered May 16, 2012 at 19:05

Maxi BaezMaxi Baez

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0

Use /\S+/g to support diacritics:

function toTitleCase(str) {
  return str.replace(/\S+/g, str => str.charAt(0).toUpperCase() + str.substr(1).toLowerCase());
}

console.log(toTitleCase("a city named örebro")); // A City Named Örebro

However: "sunshine (yellow)" ⇒ "Sunshine (yellow)"

answered Jun 20, 2016 at 20:31

le_mle_m

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I think the simplest is using css.

function format_str(str) {
    str = str.toLowerCase();
    return ''+ str +'';
}

answered Jul 7, 2017 at 5:01

wondimwondim

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3

"john f. kennedy".replace(/\b\S/g, t => t.toUpperCase())

answered Jun 21, 2019 at 8:30

ProximoProximo

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3

Here's a really simple & concise ES6 function to do this:

const titleCase = (str) => {
  return str.replace(/\w\S*/g, (t) => { return t.charAt(0).toUpperCase() + t.substr(1).toLowerCase() });
}

export default titleCase;

Works well included in a utilities folder and used as follows:

import titleCase from './utilities/titleCase.js';

const string = 'my title & string';

console.log(titleCase(string)); //-> 'My Title & String'

answered Nov 19, 2020 at 10:39

Hedley SmithHedley Smith

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1

Here is my function that is taking care of accented characters (important for french !) and that can switch on/off the handling of lowers exceptions. Hope that helps.

String.prototype.titlecase = function(lang, withLowers = false) {
    var i, string, lowers, uppers;

    string = this.replace(/([^\s:\-'])([^\s:\-']*)/g, function(txt) {
        return txt.charAt(0).toUpperCase() + txt.substr(1).toLowerCase();
    }).replace(/Mc(.)/g, function(match, next) {
        return 'Mc' + next.toUpperCase();
    });

    if (withLowers) {
        if (lang == 'EN') {
            lowers = ['A', 'An', 'The', 'At', 'By', 'For', 'In', 'Of', 'On', 'To', 'Up', 'And', 'As', 'But', 'Or', 'Nor', 'Not'];
        }
        else {
            lowers = ['Un', 'Une', 'Le', 'La', 'Les', 'Du', 'De', 'Des', 'À', 'Au', 'Aux', 'Par', 'Pour', 'Dans', 'Sur', 'Et', 'Comme', 'Mais', 'Ou', 'Où', 'Ne', 'Ni', 'Pas'];
        }
        for (i = 0; i < lowers.length; i++) {
            string = string.replace(new RegExp('\\s' + lowers[i] + '\\s', 'g'), function(txt) {
                return txt.toLowerCase();
            });
        }
    }

    uppers = ['Id', 'R&d'];
    for (i = 0; i < uppers.length; i++) {
        string = string.replace(new RegExp('\\b' + uppers[i] + '\\b', 'g'), uppers[i].toUpperCase());
    }

    return string;
}

answered Dec 11, 2016 at 16:36

OuatatazOuatataz

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here's another solution using css (and javascript, if the text you want to transform is in uppercase):

html

JOHN SMITH

js

var str = document.getElementById('text').innerHtml;
var return_text = str.toLowerCase();

css

#text{text-transform:capitalize;}

answered Oct 25, 2018 at 12:12

henriehenrie

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Taking the "lewax00" solution I created this simple solution that force to "w" starting with space or "w" that initiate de word, but is not able to remove the extra intermediate spaces.

"SOFÍA vergara".toLowerCase().replace(/\b(\s\w|^\w)/g, function (txt) { return txt.toUpperCase(); });

The result is "Sofía Vergara".

answered Sep 30, 2014 at 18:52

AserewareAsereware

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We have been having a discussion back here at the office and we think that trying to automatically correct the way people input names in the current way you want it doing is fraught with possible issues.

We have come up with several cases where different types of auto capitalization fall apart and these are just for English names alone, each language has its own complexities.

Issues with capitalizing the first letter of each name:

• Acronyms such as IBM aren’t allowed to be inputted, would turn into Ibm.

• The Name McDonald would turn into Mcdonald which is incorrect, the same thing is MacDonald too.

• Double barrelled names such as Marie-Tonks would get turned into Marie-tonks.

• Names like O’Connor would turn into O’connor.

For most of these you could write custom rules to deal with it, however, this still has issues with Acronyms as before and you get a new issue:

• Adding in a rule to fix names with Mac such as MacDonald, would the break names such as Macy turning it into MacY.

The only solution we have come up with that is never incorrect is to capitalize every letter which is a brute force method that the DBS appear to also use.

So if you want to automate the process it is as good as impossible to do without a dictionary of every single name and word and how it should be capitlized, If you don't have a rule that covers everything don't use it as it will just annoy your users and prompt people who want to enter their names correctly to go else where.

answered Jul 18, 2017 at 13:13

jjr2000jjr2000

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1