Should we store $(this) in jQuery's cache, or leave it be?

Question

Should we store $(this) in jQuery's cache, or leave it be?

When dealing with a selector such as $(this), does the act of creating and reusing a reference actually have a noticeable impact on performance?

I find it more efficient to create references for jQuery selectors that are used repeatedly within the same scope. For example:

    var jSel = $('div.some_class input.some_other_class');
    some_function1(jSel);
    some_function2(jSel);

is preferable over this approach:

    some_function1($('div.some_class input.some_other_class'));
    some_function2($('div.some_class input.some_other_class'));

But what about when the selector is simply $(this), representing a DOM element within a jQuery method? Would it be beneficial to create a reference for $(this) and reuse it, or can multiple $(this) selectors offer similar performance?

Is there a significant speed difference between:

    var jSel = $(this);
    some_function1(jSel);
    some_function2(jSel);

and:

    some_function1($(this));
    some_function2($(this));

javascript jquery

Answer 1

Answer №1

Is the following significantly quicker than this?

Not really. It's only marginally faster; just a few microseconds difference.

But does that mean you shouldn't store the result in a variable and use it? Nope. Using a variable can make it clearer what 'this' refers to and can be more convenient. Plus, if you decide to switch from operating on '$(this)' to '$(this).next()', you only need to make the change in one place instead of multiple.

The jQuery constructor is actually very optimized for taking a single DOM element as an input. Here's the precise code that runs when you call '$(DOMElement)' (after the jQuery object is created):

var match, elem, ret, doc;

// Handling $(""), $(null), or $(undefined)
if ( !selector ) {
    return this;
}

// Handling $(DOMElement)
if ( selector.nodeType ) {
     this.context = this[0] = selector;
    this.length = 1;
    return this;
}

// There are many other parameter types we could handle, but we've addressed the above case so stopping here...

Answer 2

Is the following significantly quicker than this?

Not really. It's only marginally faster; just a few microseconds difference.

But does that mean you shouldn't store the result in a variable and use it? Nope. Using a variable can make it clearer what 'this' refers to and can be more convenient. Plus, if you decide to switch from operating on '$(this)' to '$(this).next()', you only need to make the change in one place instead of multiple.

The jQuery constructor is actually very optimized for taking a single DOM element as an input. Here's the precise code that runs when you call '$(DOMElement)' (after the jQuery object is created):

var match, elem, ret, doc;

// Handling $(""), $(null), or $(undefined)
if ( !selector ) {
    return this;
}

// Handling $(DOMElement)
if ( selector.nodeType ) {
     this.context = this[0] = selector;
    this.length = 1;
    return this;
}

// There are many other parameter types we could handle, but we've addressed the above case so stopping here...

Answer 3

Answer №2

The speed of your program execution can vary depending on the number of function calls you make. It is more efficient to store a result in a variable rather than repeatedly computing it, especially when dealing with a large loop iteration like 5 million. By setting the variable once and not recalculating it each time through the loop, you can significantly improve performance in such scenarios.

Answer 4

The speed of your program execution can vary depending on the number of function calls you make. It is more efficient to store a result in a variable rather than repeatedly computing it, especially when dealing with a large loop iteration like 5 million. By setting the variable once and not recalculating it each time through the loop, you can significantly improve performance in such scenarios.

Answer 5

Answer №3

In this specific scenario, if you find yourself creating functions that require a jQuery object as an argument (like in your examples), you have the option to refactor those functions as jQuery methods instead. This way, you can simply write:

$(this).some_custom_function().another_custom_function();

Crafting jQuery methods is quite straightforward, especially for basic ones. The basic template for creating them looks like this:

jQuery.fn.custom_function = function() {
  return this.each(function() {
    // code block goes here
  });
};

Answer 6

In this specific scenario, if you find yourself creating functions that require a jQuery object as an argument (like in your examples), you have the option to refactor those functions as jQuery methods instead. This way, you can simply write:

$(this).some_custom_function().another_custom_function();

Crafting jQuery methods is quite straightforward, especially for basic ones. The basic template for creating them looks like this:

jQuery.fn.custom_function = function() {
  return this.each(function() {
    // code block goes here
  });
};

Answer 7

Answer №4

Here is a mention of the element in question. Utilizing $(here) may require some processing time (due to jQuery converting it into an array) but this delay is negligible in my opinion. Therefore, the initial approach may be slightly quicker, however, you are unlikely to discern any noticeable distinction.

Answer 8

Here is a mention of the element in question. Utilizing $(here) may require some processing time (due to jQuery converting it into an array) but this delay is negligible in my opinion. Therefore, the initial approach may be slightly quicker, however, you are unlikely to discern any noticeable distinction.

Answer 9

Answer №5

http://jsperf.com/jquery-cache-vs-no-chace

This link can provide you with a basic understanding of the speed difference between caching and not caching in jQuery. In simple cases, it may not have a significant impact on code execution speed. However, when JavaScript performance is crucial, every optimization counts. It's always beneficial to incorporate good practices into your coding routine!

Answer 10

http://jsperf.com/jquery-cache-vs-no-chace

This link can provide you with a basic understanding of the speed difference between caching and not caching in jQuery. In simple cases, it may not have a significant impact on code execution speed. However, when JavaScript performance is crucial, every optimization counts. It's always beneficial to incorporate good practices into your coding routine!

Answer 11

Answer №6

Here's a quick comparison:

Answer 12

Here's a quick comparison:

Should we store $(this) in jQuery's cache, or leave it be?

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

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