Various ways to declare functions in JavaScript

Question

Various ways to declare functions in JavaScript

1)Function declaration with variable name:

var x = function (a, b) {return a * b};

2)Another type of function in JavaScript within Angular1:


var method = {
    add_category: function(data, success, failure) {
        $upload.upload({
            url: baseUrl() + 'add_category',
            data: data
        }).success(success).error(failure);
    },
    fileupload: function(data, success, failure) {   
        $upload.upload({
            url: baseUrl() + 'ImageUpload',
            data: data
        }).success(success).error(failure);
    }
    return method;
}

What is the difference between these two code examples? In the first method (option 1), values are assigned to one variable using var x = function(a, b). For the second code (option 2), how does it work with semicolons like fileupload: function(data, success, failure)? How is the data assigned in the fileupload variable?

javascript angularjs

Answer 1

Answer №1

Within the realm of JavaScript, a function holds the esteemed status of being considered a "first class citizen," much like a string, number, or object. This means it can be treated just like any other variable - assigned to a variable and utilized wherever a variable is expected.

To illustrate this concept:

var obj = {
    item1: 10,
    item2: "string",
    item3: function (a,b) { return a*b; }
}

We are essentially creating an object with three distinct properties: a numerical value, a string, and a function. This concept is akin to:

var fn = function (a,b) { return a*b; };

var obj = {
    item1: 10,
    item2: "string",
    item3: fn
}

When you want to invoke this function, you would do so in the following manner:

var prod = obj.item3(2,4); // outputs 8

Answer 2

Within the realm of JavaScript, a function holds the esteemed status of being considered a "first class citizen," much like a string, number, or object. This means it can be treated just like any other variable - assigned to a variable and utilized wherever a variable is expected.

To illustrate this concept:

var obj = {
    item1: 10,
    item2: "string",
    item3: function (a,b) { return a*b; }
}

We are essentially creating an object with three distinct properties: a numerical value, a string, and a function. This concept is akin to:

var fn = function (a,b) { return a*b; };

var obj = {
    item1: 10,
    item2: "string",
    item3: fn
}

When you want to invoke this function, you would do so in the following manner:

var prod = obj.item3(2,4); // outputs 8

Various ways to declare functions in JavaScript

Answer №1

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