这段代码有什么问题？ 当我运行它的结果只是显示0
[英]what is wrong in this code? when i run it just shows 0 as the result
问题描述
what is wrong in this code? 
这段代码有什么问题？ when i run it just shows 0 as the result.i have checked with every known possible error.multiplication result is shown as zero. 当我运行时，结果仅显示0.我已经检查了每个已知的可能错误。乘法结果显示为零。
<html>
<head>
<title>Calculate</title>
<style>
</style>
</head>
<body>
<p>1st Number:<input type="text" id="firstNumber"></p>
<p>2nd Number:<input type="text" id="secondNumber"></p>
<button id="m">Multiply</button>
<button id="d">divide</button>
<p id="num"></p>
<script>
var firstNumber,secondNumber;
firstNumber=document.getElementById("firstNumber").value;
secondNumber=document.getElementById("secondNumber").value;
document.getElementById("m").onclick=function()
{
document.getElementById("num").innerHTML=firstNumber*secondNumber;
}
document.getElementById("d").onclick=function()
{
document.getElementById("num").innerHTML=firstNumber/secondNumber;
}
</script>
</body>
</html>
2 个解决方案
解决方案1
1 已采纳 2016-06-04 19:25:41
firstNumber and secondNumber are always empty strings, as you get them before someone clicks. firstNumber和secondNumber始终是空字符串，因为您在有人单击之前会得到它们。
You have to get the values when someone clicks 当有人点击时，您必须获取值
document.getElementById("m").onclick = function() {
var firstNumber = document.getElementById("firstNumber").value;
var secondNumber = document.getElementById("secondNumber").value;
document.getElementById("num").innerHTML = firstNumber * secondNumber;
}
document.getElementById("d").onclick = function() {
var firstNumber = document.getElementById("firstNumber").value;
var secondNumber = document.getElementById("secondNumber").value;
document.getElementById("num").innerHTML = firstNumber / secondNumber;
}
You should preferably use addEventListener instead of inline javascript 您最好使用addEventListener而不是内联javascript
解决方案2
1 2016-06-04 19:27:51
Make variables firstNumber and secondNumber pointers on your elements instead of retrieving values from outside the functions. 在元素上创建变量firstNumber和secondNumber指针，而不是从函数外部检索值。 That way you can access the value of the elements inside the functions. 这样，您可以访问函数内元素的值。
var firstNumber, secondNumber; firstNumber = document.getElementById("firstNumber"); secondNumber = document.getElementById("secondNumber"); document.getElementById("m").onclick = function() { document.getElementById("num").innerHTML = firstNumber.value * secondNumber.value; } document.getElementById("d").onclick = function() { document.getElementById("num").innerHTML = firstNumber.value / secondNumber.value; }
<html> <head> <title>Calculate</title> <style> </style> </head> <body> <p>1st Number: <input type="text" id="firstNumber"> </p> <p>2nd Number: <input type="text" id="secondNumber"> </p> <button id="m">Multiply</button> <button id="d">divide</button> <p id="num"></p> </body> </html>
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