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<title>用typeof查看数据类型</title>
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pre{color:green;padding:10px 15px;background:#f0f0f0;border:1px dotted #333;font:12px/1.5 Courier New;}
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<pre>
<script type="text/javascript">
alert(typeof 12345); <span>//输出number</span>
alert(typeof "abc"); <span>//输出string</span>
alert(typeof document); <span>//输出object</span>
</script>
</pre>
<script>
alert("typeof 12345 → " + typeof 12345 + "\
\n\ntypeof \"abc\" → " + typeof "abc" + "\
\n\ntypeof document → " + typeof document
);
</script>
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用parseInt解析数字，并求和
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<title>用parseInt解析数字，并求和</title>
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body{font:12px/1.5 arial;text-align:center;}
.f-text{width:50px;border:1px solid #ccc;background:#f0f0f0;font-family:inherit;padding:3px;}
span{color:green;padding-right:10px;font-weight:700;}
strong{padding:0 10px;}
</style>
<script type="text/javascript">
window.onload = function ()
{
var aInput = document.getElementsByTagName("input");
var aSpan = document.getElementsByTagName("span")[0];
var i = 0; for (i = 0; i < aInput.length - 1; i++)
{
aInput[i].onkeyup = function ()
{
this.value = this.value.replace(/[^\d]/,"")
}
} aInput[2].onclick = function ()
{
(aInput[0].value == "" || aInput[1].value == "") ?
alert("请输入数字！") :
aSpan.innerHTML = parseInt(aInput[0].value) + parseInt(aInput[1].value);
}
};
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<input type="text" class="f-text" /><strong>+</strong><input type="text" class="f-text" /><strong>=</strong><span>?</span><input type="button" value="求和" />
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