What is the usage of Function.prototype.bind in JavaScript ?

Bind method: Using this method, we can bind an object to a common function, so that gives different result when its needed. The bind() method takes an object as an argument and creates a new function. So basically bind function return function.

Let’s understand when bind method is used.

bind the object with common function

Example 1:

Javascript

<script>
    const gfg = {
        name: "javascript",
        content: "prototype",
        feature: function () {
            console.log(
                `Help in learning ${this.name}.
                The topic is ${this.content}`
            );
        }
    }

    // Simple method to feature of gfg object
    gfg.feature();
    console.log()

    // Try to bind gfg object property feature
    // to other common function so that it
    // used for later use but it does not
    // happen here
    let b = gfg.feature;
    b();
    console.log()

    // Now try to bind object using bind
    // method
    // bind method first argument refer
    // object that's why parameter gfg object
    let c = gfg.feature.bind(gfg);
    c();
</script>

Note: Bind different objects to a common function so that each object can access that function and extra functionality to objects so bind function takes any number of arguments.

Example 2: 

Javascript

<script>
    const gfg = {
        name: "javascript",
        content: "prototype",
    }

    const gfg1 = {
        name: "c++",
        content: "inheritance",
    }

    const gfg2 = {
        name: "java",
        content: "applet",
    }

    // Function which is binding with different object
    function features(param) {
        console.log(`Help in learning ${this.name}.
        The topic is ${this.content} and
         these are help in ${param}`)
    }

    // Binding obj1 abd extra functionality
    let bindfunc = features.bind(gfg);

    bindfunc("placement");

    // Binding obj2
    let bindfunc1 = features.bind(gfg2);
    bindfunc1("placement");
</script>