How to write function calling function in jquery

<p>jQuery is now a very mature JavaScript class library, which can greatly improve the efficiency and quality of JavaScript code writing. In the process of using jQuery, you often need to call some jQuery functions. This article will introduce how to write elegant jQuery function calling functions.

<p>1. Basic knowledge

<p>Before using jQuery, you need to ensure that the jQuery library has been introduced, such as:

<script src="https://code.jquery.com/jquery-3.5.1.min.js"></script>

<p>First, we need to understand each function in jQuery They are all an object, and the object can be passed into another function as a parameter, thus forming a nested call of the function. This method is called a function callback. For example:

$('button').click(function() {
  alert('Click detected!');
});

<p>In the above code, we bind click events to all button elements in the page through the $('button').click() function , when a button element is clicked, JavaScript will automatically execute the processing function set inside the click() function (that is, alert('Click detected!') ).

<p>2. Nested calling of functions

<p>In jQuery, we often need to call another callback function within a callback function. In this case, we can use nested calls of functions to achieve this. For example:

$('button').click(function() {
  $('p').hide('slow', function() {
    alert('The paragraph is now hidden.');
  });
});

<p>In the above code, we bind click events to all button elements on the page and set a callback function. When a button element is clicked, JavaScript will automatically execute the $('p').hide() function set inside the callback function. When the $('p').hide() function is executed, the callback function within the function will be automatically executed and a prompt box will pop up.

<p>3. Pass functions as parameters

<p>In jQuery, functions can be passed as parameters to other functions. This technique is widely used to achieve various effects and operations. For example:

function myFunction(callback) {
  // 执行操作...
  callback(); // 调用回调函数
}

myFunction(function() {
  alert('Hello, world!');
});

<p>In the above code, we define a function myFunction(), in which the callback parameter is a callback function. When this function is called, the set operation will be performed, and then the callback function callback() will be automatically called. And when we call the myFunction() function, we pass an anonymous function function() {alert('Hello, world!');} to callbackparameter.

<p>4. Chain calls of function calls

<p>In jQuery, functions can also be connected through chain calls, making them more concise and elegant to use. For example:

$('p').hide().delay(5000).show();

<p>In the above code, we continuously called $('p').hide(), delay(5000) and show( )Three functions make all <p> elements automatically hidden and then automatically displayed after 5 seconds.

<p>5. Closure

<p> Closure (Closure) is a feature widely used in JavaScript, which can provide a more flexible way of defining and calling functions. In jQuery, we can use closures to implement some advanced operations. For example:

(function(){
  // 内部定义的变量和函数（闭包）
})();

<p>In the above code, we define an anonymous function and execute it immediately. In this anonymous function, we can define various variables and functions and protect them from external interference through closure (that is, defining functions inside the function).

<p>6. Summary

<p>Through the above examples, we have learned how to correctly perform nested calls of functions, passing functions as parameters, chain calls and closures of function calls in jQuery. Mastering these techniques can make our code more elegant and flexible, and improve the efficiency of our code programming.

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