JavaScript assert() function
我第一次看到是在 John Resig 那个Online advanced Javascript learning中看到这样的使用方法,网上翻了翻,明白了构成,在平时测试时其实还蛮有用.
具体的实现方式如下:
HTML:
<ul>
<li class="pass">this is for what is true</li>
<li class="fail">this is for what is false</li>
</ul>
CSS:
.pass:before{
content:"PASS: ";
color:green;
font-weight:bold;
}
.fail:before{
content:"FAIL: ";
color:red;
font-weight:bold;
}
JavaScript:
function assert( condition, description ) { //condition为传入判断true or false 的语句,description为string
var output = document.getElementById('forTest'); //找到Ul元素
var li = document.createElement('li'); //create li 元素
li.className = condition? 'pass' : 'fail'; // 判断condition为何值,true则li为pass的类,false则为fail的类,
var des=document.createTextNode( description ) ; // 为传入的description定义到变量desp,crteate text node
li.appendChild(des); // 接下来的两步就没有什么好说的了
output.appendChild(li);
};
//试一下这个
var a = 5,b,c=5;
assert(a=b,"this is true");
assert(a=c,"this is false");