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Be proficient in the skills of this keyword in jQuery

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Release： 2024-02-24 12:09:08

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Be proficient in the skills of this keyword in jQuery

Decrypt the usage tips of this in jQuery

In the process of using jQuery, you often encounter the use of this keyword. This is a very important keyword, which represents the currently selected element, but in different situations, the pointer of this may be different. It is very important to understand how to use this keyword correctly. This article will decrypt the usage skills of this in jQuery through specific code examples to help readers better understand and master the use of this.

This in the click event

In jQuery, click events are often used. When we bind a click event to an element, we can access the currently clicked element through the this keyword. For example:

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>点击事件中的this</title>
<script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
<script>
$(document).ready(function(){
  $("#btn").click(function(){
    alert($(this).text());
  });
});
</script>
</head>
<body>

<button id="btn">点击我</button>

</body>
</html>

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In the above code, when the button is clicked, the pop-up prompt box will display "Click me", indicating that this points to the currently clicked button element.

This in traversal elements

When using jQuery’s traversal method, this represents the element currently being processed. For example, in the each method, this represents the currently traversed element. An example is as follows:

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>遍历元素中的this</title>
<script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
<script>
$(document).ready(function(){
  $("li").each(function(){
    alert($(this).text());
  });
});
</script>
</head>
<body>

<ul>
  <li>第一项</li>
  <li>第二项</li>
  <li>第三项</li>
</ul>

</body>
</html>

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In the above example, the each method traverses the li elements under the ul element, and through this you can obtain the text content of the li element currently being processed.

Change the pointer of this

Sometimes, you need to change the pointer of this in the event processing function. You can use the proxy method provided by jQuery. accomplish. An example is as follows:

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>改变this的指向</title>
<script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
<script>
$(document).ready(function(){
  var obj = {
    value: "Hello",
    showMessage: function(){
      alert(this.value);
    }
  };

  $("#btn").click($.proxy(obj.showMessage, obj));
});
</script>
</head>
<body>

<button id="btn">点击我</button>

</body>
</html>

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In the above example, the this of the obj.showMessage method is pointed to the obj object through the $.proxy method, and "Hello" will pop up when the button is clicked.

Through the above specific code examples, I hope readers will have a deeper understanding of the usage of this in jQuery. The correct use of this keyword can allow us to operate DOM elements more flexibly and improve development efficiency. We hope readers will practice and apply more in actual development to master the usage skills of this.

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