animate method in jquery

jQuery is a popular JavaScript library that provides developers with many easy ways to manipulate DOM elements and perform animations. Among them, the animate() method is a very commonly used method. It is used to gradually change the CSS attribute value of an element within a specific period of time to achieve animation effects. In this article, we will take an in-depth look at the animate() method, including syntax, parameters, and usage.

Grammar

The basic syntax of the animate() method is as follows:

$(selector).animate({properties}, speed, easing, callback)

Here is an explanation of each parameter:

• selector: Required, one or more elements to animate.
• properties: Required, an object that specifies one or more CSS properties and their values.
• speed: Optional, specifies the execution speed of the animation, which can be "slow", "fast" or a millisecond value.
• easing: Optional, specifies the easing function of the animation, which can be "swing" or "linear" or the name of a custom function.
• callback: Optional, function to be executed when the animation is completed.

In addition to the basic syntax above, the animate() method can accept many other parameters and options.

Parameters

The following are some common parameters that can be used in the animate() method:

• step: used during the animation process Functions that perform other operations are called once every frame. This function has two parameters, the first parameter represents the progress of the current frame, and the second parameter represents the value of the current element.
• queue: A Boolean value indicating whether the animation should start after the previous animation has completed. Defaults to true.
• start: A function that performs some operations before the animation starts.
• progress: A function that is called periodically during the animation process. It will be called once every frame. This function has three parameters. The first parameter represents the progress of the current frame, the second parameter represents the value of the current element, and the third parameter represents the current time.
• done: A function that is executed after the animation is completed.
• fail: A function that is executed when the animation fails.
• always: A function that is executed when the animation completes or fails.

In addition to these parameters, the animate() method can also accept some other options, such as:

• duration: Specify the duration of the animation, Can be a millisecond value or "fast" or "slow".
• easing: Specify the name of the animation easing function or a custom function.
• complete: Specify the callback function to be called when the animation is completed.
• queue: Specifies whether the animation can be added to the queue.
• specialEasing: Specify the easing function for a specific CSS property.

Usage

Here are some practical use cases of the animate() method:

1. Change the width and height of the element

$("div").animate({
  width: "200px",
  height: "200px"
}, 1000);

This code snippet will select all <div> elements and take 1000 milliseconds to change their width and height to 200 pixels.

2. Change the transparency and position of the element

$("#element").animate({
  opacity: 0.5,
  left: "+=50",
  top: "+=50"
}, 1000);

This code snippet will select an element with the id "element" and then use 1000 milliseconds to change its transparency Change it to 0.5, move it 50 pixels left and 50 pixels up.

3. Chain animation

$(".first").animate({left: "100px"}, 1000)
           .animate({top: "50px"}, 1000)
           .animate({height: "200px"}, 1000);

This code snippet will select elements with class "first" and then move them 100 pixels to the left and then 50 pixels up pixels and finally change its height to 200 pixels. In addition, these animations are executed after the previous animation is completed.

4. Using the callback function

$("button").click(function(){
  $("div").animate({
    width: "200px",
    height: "200px"
  }, 1000, function(){
    alert("动画完成！");
  });
});

This code snippet will select all <div> elements when the user clicks the button, and then It takes 1000 milliseconds to change their width and height to 200 pixels. When the animation is completed, a prompt box will pop up.

Summary

In this article, we learned about the animate() method in jQuery. It is a very common method used to gradually change the shape of an element within a specific period of time. CSS property values ​​to achieve animation effects. We learned about its syntax, parameters and usage, and looked at some practical examples. Proficient in the animate() method, we can add vivid and attractive animation effects to our website.

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