In Object Oriented JavaScript, everything is an object and therefore we can set and access additional properties to functions and methods via the prototype
Call( ): The call() method invokes a function with a given 'this' value and arguments provided one by one. This means that we can call any function, and explicitly specify what 'this' should reference within the calling function.
Apply( ): Invokes the function and allows you to pass in arguments as an array.
Bind(): returns a new function, allowing you to pass in an array and any number of arguments.
When we use the bind() method:
1.The JS engine is creating a new invite instance and binding friend1 and friend2 as its 'this' variable. So basically it copies the invite function.
2.After creating a copy of the invite function it is able to call inviteFriend1( ) and inviteFriend2( ), although it wasn’t on the friend1 and friend2 object initially. It will now recognizes its properties and its methods.
Call and apply are pretty interchangeable. Both execute the current function immediately. You need to decide whether it’s easier to send in an array or a comma separated list of arguments. Whereas Bind creates a new function that will have this set to the first parameter passed to bind().
Thank You!
Top comments (6)
So, I know how these functions work, but I can't quite figure out when they are useful
when would you want to use call(function, arg) instead of function(arg)?
We use call, bind and apply methods to set the 'this' keyword independent of how the function is called. This is especially useful for the callbacks. Also, functions are a special kind of objects in JavaScript. So they have access to some methods and properties. Call, bind, and apply are some of the methods that every function inherits.
ah, got it
really hadn't thought about callbacks, but that makes some sense
Sometimes the
bind()method has to be used to prevent losingthis, especially in callback. but actually, in ES6 we use the arrow function instead of bind hack to avoid such unwanted mistakes!✌Really helpful article!!
Thank you. I am glad it helped