HTML5 + Jscript与JQuery，setInterval问题
在我把桌子上的所有东西都扔出去之前，请有人告诉我为什么这不起作用。
我有以下 html 文档：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html"; charset=utf-8 />
<title>Sample Gauge using JQuery</title>
</head>
<body>
<canvas id="gauge" width="200" height="200">
Your web browser does not support HTML 5 because you fail.
</canvas>
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript" src="gauge.js"></script>
</body>
</html>
并且 gauge.js:
$(document).ready(function () {
//(canvas gets assigned)
startRendering();
function startRendering() {
setInterval("render();", 1000);
}
function render() {
renderBackground();
renderNeedle(-172);
}
//(Defined functions for rendering a gauge)
});
render() 不会被调用，但如果我将 setInterval 行更改为“render()”，它就会被调用。 另外，如果我更改 setInterval() 以包含类似“alert('LOL')”的内容，那么它确实可以工作，但它似乎不适用于我定义的函数。 要调用的函数末尾有或没有分号没有区别，前缀 this 也没有区别。我的职能。
我正在尝试让它工作，这样我就可以开始使用它来制作仪表动画。谁能看出为什么它不起作用？
我讨厌网络开发。
Please can someone tell me why this isn't working before I defenestrate everything on my desk.
I have the following html document:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html"; charset=utf-8 />
<title>Sample Gauge using JQuery</title>
</head>
<body>
<canvas id="gauge" width="200" height="200">
Your web browser does not support HTML 5 because you fail.
</canvas>
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript" src="gauge.js"></script>
</body>
</html>
And gauge.js:
$(document).ready(function () {
//(canvas gets assigned)
startRendering();
function startRendering() {
setInterval("render();", 1000);
}
function render() {
renderBackground();
renderNeedle(-172);
}
//(Defined functions for rendering a gauge)
});
render() does not get called, but if I change the setInterval line to just 'render()' it does.
Also, if I change setInterval() to contain something like "alert('LOL')" then it does work, it just doesn't seem to work with functions I have defined.
With or without a semicolon at the end of the function(s) to call makes no difference, nor does prefixing this. to my functions.
I'm trying to get this working so I can start using it to animate the gauge. Can anyone see why it isn't working?
I hate web development.
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更改
为
当您将字符串传递给 setInterval() 时，其中的代码将在当前范围之外执行。无论如何，直接传递该函数更为合适。如果去掉括号，函数可以像任何其他变量一样传递。
Change
To
When you pass a string to setInterval(), the code inside is executed outside of the current scope. It's much more appropriate to just pass the function anyway. Functions can be passed around just like any other variable if you leave the parenthesis off.
我不确定为什么仅使用“render()”不起作用，但使用此代码可以解决问题。
I'm not sure why using just "render()" doesn't work but using this code will fix the problem.