JS编程

html调用js脚本发现直接在js中写的语句，使用：

main.js:

var myHeading  = document.querySelector('h1'); //获取header元素
myHeading.title = 'hello world!';
myHeading.textContent = 'hello world!';
var iceCream = 'chocolate';
if (iceCream === 'chocolate') {
        alert('Yay, I love chocolate ice Cream');
    } else {
        alert('Awww, but chocolate is my favorite');
    }

包含在html中并不会执行,需要在js中将代码加入到函数中，在html中告知执行的时间:

var iceCream = 'chocolate';
function show() {
    if (iceCream === 'chocolate') {
        alert('Yay, I love chocolate ice Cream');
    } else {
        alert('Awww, but chocolate is my favorite');
    }
}

html:

<script type="text/javascript" language="JavaScript">
    window.onload=show();
script>