Javascript ScrollTo在页面加载时不起作用

Question

I have a issue, I want to scroll the page to a particular element once the page renders by calling window.scrollTo(). 我有一个问题，我想通过调用window.scrollTo（）将页面呈现后滚动到特定元素。 But doesn't work. 但是不起作用。 Any limitations? 有什么限制吗？

var step = Math.round(distance / 25); // distance is Stop-start
  var leapY = stopY > startY ? startY + step : startY - step;
    var timer = 0;
    if (stopY > startY) {
        for (var i = startY; i < stopY; i += step) {
            setTimeout(window.scrollTo(0,leapY), timer * speed);
            leapY += step;
            if (leapY > stopY) 
                leapY = stopY;
            timer++;
        }            
    }

Answer 1

This line: 这行：

setTimeout(window.scrollTo(0,leapY), timer * speed);

calls window.scrollTo immediately and passes its return value into setTimeout , just like foo(bar()) calls bar immediately and passes its return value into foo . 立即调用window.scrollTo并将其返回值传递给setTimeout ，就像foo(bar()) 立即调用bar并将其返回值传递给foo 。

You need to pass in a function: 您需要传递一个函数：

setTimeout(function() { window.scrollTo(0,leapY); }, timer * speed);

But that alone isn't enough, because the function will look at the leapY value as it is when it runs , not when it's defined, and so they'll all end up using the last value of leapY . 但是，仅此还不够，因为该函数将在运行时 （而不是在定义时）看待leapY值，因此它们最终都将使用最后一个leapY值。 So you want a builder function: 因此，您需要一个构建器函数：

setTimeout(buildScroller(leapY), timer * speed);

function buildScroller(y) {
    return function() { window.scrollTo(0,y); };
}

In the loop, we call the builder passing in leapY as the y argument, and it returns a function closing over the argument (rather than leapY ). 在循环中，我们所说的建设者经过leapY为y参数，并可以通过参数（而不是返回函数结束leapY ）。 That argument doesn't change, so the function it builds uses the right value. 该参数不会改变，因此它构建的函数使用正确的值。

Live Example | 现场示例 | Live Source 现场直播

<!DOCTYPE html>
<html>
<head>
<meta charset=utf-8 />
<title>Scrolling On Load In Loop</title>
  <style>
    div {
      height: 200px;
    }
  </style>
</head>
<body>
  <div>Scrolls to each of the first four followingdivs at intervals of one second</div>
  <div>0x100</div>
  <div>0x200</div>
  <div>0x300</div>
  <div>0x400</div>
  <div>0x500</div>
  <div>0x600</div>
  <div>0x700</div>
  <div>0x800</div>
  <div>0x900</div>
  <div>0x1000</div>
  <div>0x1100</div>
  <div>0x1200</div>
  <div>0x1300</div>
  <div>0x1400</div>
  <script>
    (function() {
      var leapY;

      for (leapY = 1; leapY <= 4; ++leapY) {
        setTimeout(buildScroller(leapY * 200), leapY * 1000);
      }

      function buildScroller(y) {
          return function() { window.scrollTo(0,y); };
      }
    })();
  </script>
</body>
</html>

Javascript ScrollTo在页面加载时不起作用

问题描述

1 个解决方案

解决方案1
3 已采纳 2013-07-04 07:18:28

Javascript ScrollTo在页面加载时不起作用

问题描述

1 个解决方案

解决方案1 3 已采纳 2013-07-04 07:18:28

解决方案1
3 已采纳 2013-07-04 07:18:28