Experience sharing: Clever use of is and where selectors to improve front-end programming efficiency

Experience sharing: Clever use of is and where selectors to improve front-end programming efficiency

Introduction:
In front-end development, selectors are a very important concept . They help us select the corresponding elements from the DOM (Document Object Model) and operate on them. Among them, is selector and where selector are two common selectors, which can greatly improve our programming efficiency. This article will introduce how to use these two selectors skillfully, with relevant code examples.

1. is selector:
is selector is mainly used to match whether the current element matches any selector in the given selector list. This is useful when dealing with multiple conditions being met simultaneously. The following is a code example:

// 选中所有class为container或wrapper的div元素
$('div').is('.container, .wrapper');

This code will return a Boolean value indicating whether the div element has a class of container or wrapper. In this way, we can perform corresponding operations based on conditions and improve the readability and reusability of the code.

2. Where selector:
The where selector provides a more complex filtering method. We can use functions to specify filtering conditions. This is useful when working with specific required groups of elements. The following is a code example:

// 选中所有class为box的div元素，并且高度大于100px
$('div').where(function() {
    return $(this).hasClass('box') && $(this).height() > 100;
});

In this example, the function parameter of the where selector uses a compound condition, that is, the div element needs to meet both the class of box and the height of more than 100px. In this way, we can more flexibly filter out groups of elements that meet our requirements.

3. Sample application:
In actual development, the is selector and the where selector can be used in combination to improve programming efficiency. The following is a sample application code:

// 选中所有class为item的li元素，并且它们的子元素a的链接地址包含关键词"example"
$('li').is('.item').where(function() {
    return $(this).find('a').attr('href').indexOf('example') !== -1;
});

This code will return all li elements with class item, and the link address of their child element a contains the keyword "example". We can implement further operations based on this result, such as modifying styles or binding events.

Conclusion:
Selectors are an essential tool in front-end development. We can skillfully use the is selector and where selector to improve programming efficiency. With the flexibility to filter and match elements, we can operate more specifically. I hope this article can help everyone understand and use these two selectors.

Reference:

• jQuery Documentation: [https://api.jquery.com/is/](https://api.jquery.com/is/)
• jQuery Documentation: [https://api.jquery.com/filter/](https://api.jquery.com/filter/)

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