Javascript String Compare ==有时会失败 [英] Javascript String Compare == sometimes fails

问题描述

以下代码有时可能会评估为false？

How could the following code sometimes evaluate to false?

(transport.responseText == '1' || 
 transport.responseText == 'CARD_VALID')

我的JavaScript代码：

My JavaScript code:

if (transport.responseText == '1' || 
    transport.responseText == 'CARD_VALID') {
    // do something.
}
else if (transport.responseText == 'CARD_INVALID' || 
             transport.responseText == 'INVALID_CHECKSUM') {
    // do something else....
}
else {
    new Ajax.Request('/report_error.php?responseText='+transport.responseText);
    // report error to user
}

== 在字符串相同时返回false？

What could cause JavaScript string compare == to return false when the strings are identical?

推荐答案

Double equals是在Javascript中比较字符串的适当方式，它返回false，然后在一个字符串的左侧和/或右侧可能有空格。

Double equals is the appropriate way to compare strings in Javascript, it is returning false then there may be whitespace to the left and or right of one string.

$ c> .trim（）在字符串的末尾，我的比较应该开始工作：

Put a .trim() on the end of the strings and my comparison should started working:

var panel = response.substr(0, response.indexOf("<")).trim();
if(panel == "combo"){
    //do something
}

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