Commas in Javascript - Stack Overflow

admin管理员组

文章数量:1389887

<script>

(function() {

$('html').addClass('js');

var contactForm = {

    container: $('#contact'),          <-- THIS COMMA

    init: function() {
        $('<button></button>', {
            text: 'Contact Me'
        })
            .insertAfter('article:first')
            .on('click', this.show);
    },  <---------------------------------- AND THIS COMMA

    show: function() {
        contactForm.container.show();
    }
};

contactForm.init();

})();

</script>

In the above script, I noticed:

container: $('#contact'),

Is that one way to declare a variable? Doing the following breaks the script:

var container = $('#contact');

Also, what is with the mas after the init function and the container variable (if it is a variable)?

<script>

(function() {

$('html').addClass('js');

var contactForm = {

    container: $('#contact'),          <-- THIS COMMA

    init: function() {
        $('<button></button>', {
            text: 'Contact Me'
        })
            .insertAfter('article:first')
            .on('click', this.show);
    },  <---------------------------------- AND THIS COMMA

    show: function() {
        contactForm.container.show();
    }
};

contactForm.init();

})();

</script>

In the above script, I noticed:

container: $('#contact'),

Is that one way to declare a variable? Doing the following breaks the script:

var container = $('#contact');

Also, what is with the mas after the init function and the container variable (if it is a variable)?

• javascript

Share Improve this question Follow edited May 30, 2012 at 20:22 Frédéric Hamidi 263k4242 gold badges496496 silver badges485485 bronze badges asked May 30, 2012 at 20:21 eveoeveo 2,8531515 gold badges6565 silver badges9999 bronze badges 1

• 4 This is Javascript object syntax and is not specific to jQuery. – Frédéric Hamidi Commented May 30, 2012 at 20:23

Add a ment  | 

5 Answers 5

Sorted by: Reset to default 8

This way you declare an object:

var contactForm = {
    // properties:
    property1 : value,
    property2 : value,
    property3 : value,

    // methods:
    method1 : function() {
        // ...
    },
    method2 : function() {
        // ...
    }
};

You can find more information about JavaScript objects in MDN ...and in the ments below :)

That block of code (beginning with var contactForm = {) is declaring an object using object literal notation. Commas separate the different key-value pairs in the object literal notation.

var obj = { key1: value1, key2: value2 };

Commas are used to separate name/value pairs when defining objects:

var newObj = {
  name: value,
  another_name: another_value
};

That is called Object literal notation.

Which is basically a Comma-Separated list of name/value pairs, wrapped in curly braces.

Advantage of this notation is that all data within the braces are encapsulated and not defined globally which avoids conflicts with other scripts or libraries.

Those are key:value pairs of the object contactForm you defined separated by mans

var obj = { key1 : value1, 

            key2 : value2

            method1 : function(){
              // definition
            },
            method2 : function(){
              // definition
            }
}

The thing that confused me in my early days is that what is function(){....} doing inside a variable(in this case an object) definition until I discovered functions are objects too in js which may not be the same case in language you have used earlier .

and this function function(){....} without name is called a anonymous function.

Here's a good thread on anonymous function Why do you need to invoke an anonymous function on the same line?

本文标签： Commas in JavascriptStack Overflow