如果声明不起作用？ Java脚本

Question

I have two textboxes and one button. 我有两个文本框和一个按钮。 I putt numbers in the first textbox and press the button to add the number to a total which is displayed in the second box, till it reaches 1000. But the if statement doesn't work for some reason. 我将数字放在第一个文本框中，然后按按钮以将数字添加到第二个框中显示的总数中，直到达到1000。但是由于某些原因，if语句不起作用。

This works fine: 这很好用：

<html>
<title>Ask7</title>
<script>
var total=0;

function calculate()
{

    var box1;
    box1=parseFloat(document.getElementById("box1").value);
    total=total+box1;
    document.getElementById("box2").innerHTML="";
    document.getElementById("box2").value=total;


}
</script>
<body>

<h3>Give num:</h3>
<input id="box1" type="text"></input>
<button onclick="calculate()" type="button">ADD</button>
<br>

<h3>Total:</h3>
<input id="box2" readonly="readonly" type="text"></input>
</body>
</html>

This doesn't: 这不是：

<html>
<title>Ask7</title>
<script>
var total=0;

function calculate()
{

if(total<1000)
{
    var box1;
    box1=parseFloat(document.getElementById("box1").value);
    total=total+box1;
    document.getElementById("box2").innerHTML="";
    document.getElementById("box2").value=total;
}
else
{
    alert("OVER 1000!");
    break;
}

}
</script>
<body>

<h3>Give num:</h3>
<input id="box1" type="text"></input>
<button onclick="calculate()" type="button">ADD</button>
<br>

<h3>Total:</h3>
<input id="box2" readonly="readonly" type="text"></input>
</body>
</html>

Basically I don't get why the if statement doesn't work. 基本上我不明白为什么if语句不起作用。

Answer 1

Remove the break , it doesn't belong there. 删除break ，它不属于该break 。

I think you should have your code like this: 我认为您应该具有如下代码：

var total = 0;

function calculate() {
    var box1;
    box1 = parseFloat(document.getElementById("box1").value);
    total = total + box1;
    box2 = document.getElementById("box2");
    box2.value = total;

    if (total < 1000) {
    // do something
    } else {
        alert("OVER 1000!");
        // break;
        box2.value = 0; // to clean the value after 1000
    }
}

Demo 演示版

Answer 2

...
 else {
        alert("OVER 1000!");

        box2.value = 0; // to clean the value after 1000

        total = 0; // **** also reset the global var for reuse as still adding over 1000

}

如果声明不起作用？ Java脚本

问题描述

2 个解决方案

解决方案1
1 已采纳 2013-10-12 18:05:57

解决方案2
0 2013-10-12 22:39:07

如果声明不起作用？ Java脚本

问题描述

2 个解决方案

解决方案1 1 已采纳 2013-10-12 18:05:57

解决方案2 0 2013-10-12 22:39:07

解决方案1
1 已采纳 2013-10-12 18:05:57

解决方案2
0 2013-10-12 22:39:07