Bind and call in javascript
In this article, I am going to explain how to use call, apply, and bind in JavaScript with simple examples. Show
We will also implement an example that showcases how you can create your own map function with the apply function. Without further ado, let's get started. Table of Contents
ADVERTISEMENT PrerequisitesHere are some of the things you should understand to get the most out of this article:
DefinitionsLet's look at the functions we'll be studying here a bit more closely to understand what they do. Call is a function that helps you change the context of the invoking function. In layperson's terms, it helps you replace the value of Apply is very similar to the
Bind is a function that helps you create another function that you can execute later with the new context of Now we will look at some basic examples of the call, apply, and bind functions. Then we will look at an example were we will be constructing our own function similar to the map function. ADVERTISEMENT
Here is the syntax of the
Where,
Note that if you invoke a function without any Now that we have some context around what the How to call a function with different contexts in JSConsider the below example. It consists of 3 classes –
If you look carefully, you can see that we
use the In both of these functions, we invoke the ADVERTISEMENT How to call a function with no arguments in JSConsider the below example:
In this example, we invoked the function How to Use the Apply Function in JavaScriptThe In Here is the syntax for the
Where,
As you can see above, the The first syntax is a simple one. You can pass in an array of arguments like below:
The second syntax is where we can pass in the new array object to it:
The third syntax is where we can pass in the arguments keyword:
arguments is a special object available inside a function. It contains values of the arguments that are passed to a function. You can use this keyword with the The best part about Let’s look at the same example as above, but this time we'll use the
And here is an example that showcases how you'd use the
ADVERTISEMENT How to Use the Bind Function in JavaScriptThe Here is the syntax for the
Where,
The
Now this function Let's look at a classic example of how to use a
Consider the above App component. It constitutes the following things:
If we click on the Have you ever wondered why this issue occurs? 🤔🤔 You might be expecting that we should be able to access the state of the class since
We can fix this by providing the right context of
The How to Create Your Own map FunctionNow that we have all the necessary things, let's start off by creating our Here is the syntax of the
Where,
The basic functionality of a It is a function that walks through each element of an array and applies the function that is passed as an argument. The return type of a map is again an array with Now we understand the requirements, so we can move on to create our own
Let's understand the above function bit-by-bit:
Now let's take a look at how we are going to execute our NOTE: do not follow the below approach in your production code. This can cause damage to the existing code.
Once this is done, we are good to go with executing our new map function on an array.
ADVERTISEMENT SummaryThis article showed you what the call, apply, and bind functions can do via examples. So to talk about these functions in brief:
Thank you for reading! Follow me on Twitter, GitHub, and LinkedIn. Learn to code for free. freeCodeCamp's open source curriculum has helped more than 40,000 people get jobs as developers. Get started What is difference between call apply and bind in JavaScript?Summary. call : binds the this value, invokes the function, and allows you to pass a list of arguments. apply : binds the this value, invokes the function, and allows you to pass arguments as an array. bind : binds the this value, returns a new function, and allows you to pass in a list of arguments.
What is a bind in JavaScript?bind is a method on the prototype of all functions in JavaScript. It allows you to create a new function from an existing function, change the new function's this context, and provide any arguments you want the new function to be called with.
What is Call () in JavaScript?The call() method is a predefined JavaScript method. It can be used to invoke (call) a method with an owner object as an argument (parameter). With call() , an object can use a method belonging to another object.
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