How to improve efficiency of jquery binding events

With the complexity of front-end pages, JavaScript frameworks have also developed, among which jQuery is one of the most popular frameworks. When developing with jQuery, event binding is an essential task. It allows you to better control the interactive behavior on the page, and can also improve the user experience while implementing complex interactions. However, incorrect event binding may cause performance problems and affect the response speed of the page. Therefore, in this article, we will explore how to improve the efficiency of jQuery event binding and make your website smoother.

1. Use event delegation

Event delegation is a relatively efficient way of event binding. Its principle is to bind the event to the parent element and then risk it through the event. Bubbles are used to respond to events of child elements, which can reduce the number of event bindings and improve performance. For example, suppose we have a table with several buttons that need to be bound to events. We can use the following method:

<table id="mytable">
  <tr>
    <td><button class="btn">按钮1</button></td>
    <td><button class="btn">按钮2</button></td>
    <td><button class="btn">按钮3</button></td>
  </tr>
  <tr>
    <td><button class="btn">按钮4</button></td>
    <td><button class="btn">按钮5</button></td>
    <td><button class="btn">按钮6</button></td>
  </tr>
</table>

$('#mytable').on('click', '.btn', function() {
  // 按钮的事件处理代码
});

In this example, we use jQuery's on () method to bind the click event, specify the child element selector .btn to bind the event in the second parameter, so that when the button is clicked When, the event will be triggered.

2. Caching jQuery objects

In the process of event binding, jQuery selectors are often used to select DOM elements. However, jQuery's selector engine does not cache references to DOM elements. Each selection needs to reconstruct a new jQuery object, which will have a certain impact on performance. Therefore, during the event binding process, it is recommended to cache the selected DOM elements to avoid repeated selection. For example, we can write like this:

var $myButton = $('button#mybutton');
$myButton.on('click', function() {
  // 按钮的事件处理代码
});

In this example, we cache the queried button object using the variable $myButton, and then use this variable directly when binding the event To operate elements and avoid the performance problem of repeated selection.

3. Optimizing selectors

In jQuery, the selector is a very powerful tool that can match elements on the page in various ways. However, the quality of the selector is also one of the important factors affecting the efficiency of binding events. Therefore, in practical applications, we need to optimize the selector as much as possible.

How to optimize the selector? First of all, you need to pay attention to the complexity of the selector and try to avoid using overly complex selectors, which will affect the speed of selecting elements. Secondly, you need to choose the appropriate selector according to the specific application scenario. For broad selectors, it is recommended to narrow the scope as much as possible to speed up the selection.

4. Unbinding events

Unbinding events is a common operation, but if used incorrectly, it will also affect performance. In jQuery, there are two ways to unbind events, one is to use the off() method, and the other is to use the unbind() method. The effect of these two methods is the same, but there are some detailed differences.

If you are using jQuery version greater than or equal to 1.7, it is recommended to use the off() method, because in the new version, the off() method can be better It handles event namespaces and multiple binding issues efficiently, and can unbind multiple events at one time. For example, we can use it like this:

$myButton.off('click', '.btn1');

If you are using a jQuery version less than 1.7, it is recommended to use the unbind() method, as follows:

$myButton.unbind('click');

In In practical applications, the appropriate unbundling method needs to be selected based on the actual situation.

5. Reduce the repeated execution of event responses

Sometimes, we need to repeatedly bind the same event to an element, for example, to an <input> The element is bound to both keyup and change events. In this case, if not handled, the event processing function will be executed repeatedly, affecting performance. In this case, you can use the debounce() method to solve the problem, which prevents the event from being triggered repeatedly. For example, the following code can make the event handler execute at most every 500 milliseconds:

function handler() {
  // 处理函数
}

$('input').on('keyup change', $.debounce(500, handler));

In this example, we use jQuery's on() method to bind keyup and change events, and then use the debounce() method to make the processing function execute at most once every 500 milliseconds, thus effectively reducing the number of event responses. It should be noted that using the debounce() method will increase a certain delay and may affect the user experience, so you need to decide whether to use it based on specific needs.

To sum up, improving the efficiency of jQuery event binding can start from many aspects, including using event delegation, caching jQuery objects, optimizing selectors, reasonably unbinding events and reducing repeated execution of event responses. If these techniques can be used properly, the response speed of the page can be greatly improved and provide users with a better experience.

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