What is the equivalent of jQuery's .before() function in Javascript?

Question

What is the equivalent of .before() in Javascript?

In its simplest form, `a.before(b)` is `a.parentNode.insertBefore(b,a)` — Niet the Dark Absol, Mar 14 '14 at 13:50
[MDN: Node.insertBefore(newElement, referenceElement)](https://developer.mozilla.org/en-US/docs/Web/API/Node.insertBefore) — t.niese, Mar 14 '14 at 13:51
You can always look at [the source](http://code.jquery.com/jquery-1.11.0.js) — Jason P, Mar 14 '14 at 13:51
https://github.com/jquery/jquery/blob/a96d5bed58f2b30f97d6dd2f5691cd890f62b75f/src/manipulation.js#L342 — j08691, Mar 14 '14 at 13:53
Check the jquery source https://github.com/jquery/jquery/blob/a96d5bed58f2b30f97d6dd2f5691cd890f62b75f/src/manipulation.js#L342 — Aamir Afridi, Mar 14 '14 at 13:53
Seems it is a duplicate... check @ http://stackoverflow.com/questions/19315948/insert-html-before-element-in-javascript-without-jquery — JQuery Guru, Mar 14 '14 at 13:54

score 8 · Accepted Answer · answered Mar 14 '14 at 13:52

node.insertBefore() is pretty much the equivalent : https://developer.mozilla.org/en-US/docs/Web/API/Node.insertBefore

$('#id').before('something');
//equivalent 
var node = document.getElementById('id');
node.parentNode.insertBefore('something', node);

Here what jQuery does : https://gist.github.com/kagagnon/a13de27760ba1af883c0#file-gistfile1-js-L6064

before: function() {
    return this.domManip( arguments, function( elem ) {
        if ( this.parentNode ) {
            this.parentNode.insertBefore( elem, this );
        }
    });
}

score 2 · Answer 2 · answered Mar 14 '14 at 13:54

2

you can use insertBefore in javascript

node.insertBefore(newnode, existingchild);

The example above will append newnode as a child of node, directly before the existingchild node.

answered Mar 14 '14 at 13:54

Arjit

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Daniel Tonon · Answer 3 · 2018-08-23T08:30:20.703

Ok these answers were a bit deceptive. It’s a bit different using node.insertBefore than using the jQuery .before() method.

// jQuery
$('.element').before('<span class="class-name">Some text</span>');

// Pure JS
var _$element = document.querySelector('.element');
var _$new = document.createElement('span');
_$new.outerHTML = '<span class="class-name">Some text</span>';
_$element.parentNode.insertBefore(_$new, _$element);

If you are wondering why it looks so simple in the jQuery snippet

before: function() {
    return this.domManip( arguments, function( elem ) {
        if ( this.parentNode ) {
            this.parentNode.insertBefore( elem, this );
        }
    });
}

Well notice that it starts with this.domManip. It is doing stuff behind the scenes in that function that abstracts away the element creation stuff.

What is the equivalent of jQuery's .before() function in Javascript?

3 Answers3