Functions as Value in JavaScript

Before reading this article, you may want to go through the following articles:

• Invocation Patterns in JavaScript
• What is Call() Method in JavaScript
• What is Bind Method in JavaScript
• Objects in JavaScript
• Optional Parameter in JavaScript Function
• Higher-Order function in JavaScript
• Deleting Properties of JavaScript object

JavaScript Functions:

1. Can be defined
2. Can be invoked

Apart from this, JavaScript functions can be treated as values as well. JavaScript functions act as values. They can be:

1. Assigned to a variable
2. Set as a property of an Object
3. Passed as argument to other function
4. Returned from a function
5. and so on...

Let us say there is a function as below:

function FindGrade(e)
{
    if (e > 60)
        return "Grade A"
    else
        return "Grade B"
}

You can assign this function to a variable as in the following:

var abc = FindGrade;
var result1 = FindGrade(20);
alert(result1);
var result2 = abc(70);
alert(result2);

You can assign a function as an Object property also. This can be done as in the following:

var obj =
    {
        grade : FindGrade
    }
        var result = obj.grade(70);
        alert(result);

You see that in the above we assigned a JavaScript function as an Object's Property. You can use a JavaScript function as an argument of another function etc. I hope you find this article useful. Thanks for reading.