javascript的計算機eval
本帖最后由 tim92087p 于 2014-09-21 17:26:05 编辑

<scriptlanguage="javascript">
functioncompute(obj)
{obj.expr.value=eval(obj.expr.value)}
varone='1'
vartwo='2'
varthree='3'
varfour='4'
varfive='5'
varsix='6'
varseven='7'
vareight='8'
varnine='9'
varzero='0'
varplus='+'
varminus='-'
varmultiply='*'
vardivide='/'
vardecimal='.'
functionenter(obj,string)
{obj.expr.value+=string}
functionclear(obj)
{obj.expr.value=''}
</script>
<formname="calc">
<tableborder=1>
<tdcolspan=4><inputtype="text"name="expr"size=30action="compute(this.form)"><tr>
<td><inputtype="button"value="7"onClick="enter(this.form,seven)">
<td><inputtype="button"value="8"onClick="enter(this.form,eight)">
<td><inputtype="button"value="9"onClick="enter(this.form,nine)">
<td><inputtype="button"value="/"onClick="enter(this.form,divide)">
<tr><td><inputtype="button"value="4"onClick="enter(this.form,four)">
<td><inputtype="button"value="5"onClick="enter(this.form,five)">
<td><inputtype="button"value="6"onClick="enter(this.form,six)">
<td><inputtype="button"value="*"onClick="enter(this.form,multiply)">
<tr><td><inputtype="button"value="1"onClick="enter(this.form,one)">
<td><inputtype="button"value="2"onClick="enter(this.form,two)">
<td><inputtype="button"value="3"onClick="enter(this.form,three)">
<td><inputtype="button"value="-"onClick="enter(this.form,minus)">
<tr><tdcolspan=2><inputtype="button"value="0"onClick="enter(this.form,zero)">
<td><inputtype="button"value="."onClick="enter(this.form,decimal)">
<td><inputtype="button"value="+"onClick="enter(this.form,plus)">
<tr><tdcolspan=2><inputtype="button"value="="onClick="compute(this.form)">
<tdcolspan=2><inputtype="button"value="AC"size=3onClick="clear"(this.form)">
</table>
</form>

{obj.expr.value=eval(obj.expr.value)}

這一段我不理解是怎麼讓他算出正確的四則運算

functionenter(obj,string)
{obj.expr.value+=string}

然後這段大概是使用為"正"的數字
------解决思路----------------------
是的
eval就是将一个字符串当做程序执行