JavaScript function animation effects: achieving a smooth user experience

JavaScript function animation effect: achieving a smooth user experience

Introduction:
In modern web development, animation effects are important for improving user experience and attracting user attention force plays an important role. JavaScript functions are an important way to achieve animation effects. This article will introduce how to use JavaScript functions to achieve smooth animation effects and give specific code examples.

1. Use timers and CSS property changes to achieve animation effects
Timers are commonly used tools to achieve animation effects. They can continuously change the CSS properties of elements within a specified time interval to achieve animation effects. The following is a sample code to achieve a simple upward sliding animation effect by changing the height attribute of the element:

function slideUp(element, duration) {
  var start = performance.now();
  var elementHeight = element.offsetHeight;

  var timer = setInterval(function() {
    var timePassed = performance.now() - start;
    var progress = timePassed / duration;

    if (progress > 1) {
      progress = 1;
    }

    element.style.height = elementHeight * (1 - progress) + 'px';

    if (progress === 1) {
      clearInterval(timer);
    }
  }, 10);
}

In the above code, the slideUp function accepts two parameters: the one to be animated The duration of elements and animations. Inside the function, we use the setInterval function to create a timer that executes every 10 milliseconds. In the timer's callback function, we calculate the progress of the animation and change the height attribute of the element based on the progress. When the progress is 1, the timer is cleared and the animation ends.

2. Use the requestAnimationFrame function to improve the animation effect
Although the timer can achieve simple animation effects, it is not the best method. Using the requestAnimationFrame function can make better use of the browser's rendering mechanism and provide smoother animation effects. The following is a sample code improved using the requestAnimationFrame function:

function smoothSlideUp(element, duration) {
  var start = null;
  var elementHeight = element.offsetHeight;

  function slide(timestamp) {
    if (!start) {
      start = timestamp;
    }

    var progress = (timestamp - start) / duration;
    
    if (progress > 1) {
      progress = 1;
    }

    element.style.height = elementHeight * (1 - progress) + 'px';

    if (progress < 1) {
      requestAnimationFrame(slide);
    }
  }

  requestAnimationFrame(slide);
}

In the above code, we define a new function smoothSlideUp, which uses requestAnimationFrame function to perform animation. requestAnimationFrameThe function will call the specified callback function before the browser redraws next time, which can ensure the smoothness of the animation. In the callback function, we calculate the progress of the animation and change the height property of the element. If the animation progress is less than 1, we will call the requestAnimationFrame function again to continue the animation until the animation ends.

Conclusion:
Through the above sample code, we can see that it is not complicated to use JavaScript functions to achieve animation effects. Using timers or requestAnimationFrame functions combined with changing CSS properties can achieve various interesting animation effects and improve user experience. In actual development, choosing the appropriate animation implementation method according to specific needs can effectively increase the attractiveness of the web page and user retention rate.

Reference materials:

• [MDN Web Documentation: Timing and Animation](https://developer.mozilla.org/zh-CN/docs/Web/API/Animation_timing_API)
• [W3School JavaScript Timing Events](https://www.w3schools.com/js/js_timing.asp)

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