关于javascript：如何执行不区分大小写的字符串比较？


How to perform a case insensitive string comparison?

本问题已经有最佳答案，请猛点这里访问。

我的网站上有一个文本框，用户可以输入命令。但问题是命令是区分大小写的。如何使命令不区分大小写？这是我的代码：

JavaScript：

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function showAlert() {

    var txtCtrl = document.getElementById("textbox1");

    var txtVal = txtCtrl.value;

    if (txtVal == '') {
        alert('Please fill in the text box. For a list of commands type"Help" into the text box.');
    }else if (txtVal == 'Start' || txtVal == 'start') {
        alert('Hello. What would you like me to do?');
    }else if (txtVal === 'Weather' || txtVal === 'weather') {
        window.location ="https://www.google.com/#q=weather";
    }else if (txtVal === 'Time' || txtVal === 'time') {
        alert('The current time according to your computer is' + formatTime(new Date()));
    }else if (txtVal === 'Help' || txtVal === 'help') {
        window.location ="help/index.html";
    }else if (txtVal === 'Donate' || txtVal === 'donate') {
        window.location ="donate/index.html";
    }else if (txtVal === 'www.' || txtVal === 'WWW.') {

    }else{
        alert('Sorry, I do not reconise that command. For a list of commands, type"Help" into the text box.');
    }
}
//Show time in 24hour format
function showTime(){
  var today = new Date();
  var h = today.getHours();
  var m = today.getMinutes();
  return [ h, m ].join(':')
}
//Show time in 12hour format
var formatTime = (function () {
    function addZero(num) {
        return (num >= 0 && num < 10) ?"0" + num : num +"";
    }

    return function (dt) {
        var formatted = '';

        if (dt) {
            var hours24 = dt.getHours();
            var hours = ((hours24 + 11) % 12) + 1;
            formatted = [formatted, [addZero(hours), addZero(dt.getMinutes())].join(":"), hours24 > 11 ?"PM" :"AM"].join("");            
        }
        return formatted;
    }
})();

和HTML：

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<!doctype html>
<html>
<head>
Random Project
</head>
<style type="text/css">
body {
    margin:0;
    font-family: arial, sans-serif;
    padding-top: 80px;
}
.container {
    margin:auto;
    text-align:center;
}
.logo {
    margin:auto;
    width:512px;
    text-align:center;
    padding-bottom:0px;
}
#textbox1 {
    border: 1px solid #ddd;
    border-radius: 0px 0px 0px 0px;
    width: 512px;
    padding-top: 5px;
    padding-bottom: 5px;
    padding-left: 7px;
    padding-right: 7px;
    height: 20px;
    font-size: 16px;
    outline: none;
    font-family: arial, sans-serif;
}
#textbox1:focus {
    border: 1px solid #0266C8;
}
#button1 {
    margin-top: 22px;
    padding: 2px 10px 2px 10px;
    outline:none;
    background-color:#eee;
    border:1px solid #ddd;
    border-radius:2px;
}
#button1:hover {
    background-color: #f5f5f5;
}
#button1:focus {
    border: 1px solid #0266C8;
}
#button1_text {
    font:bold 11px/27px Arial,sans-serif!important;
    color:#333;
}
.information {
    font-size:12px;
    color:#555;
}
.separator {
    height:100px;
}
.tip {
    color:green;
    font-weight:bold;
    font-size:12px;
    margin-top:10px;
}
.tip_text {
    color:#111;
    font-weight:normal;
}
</style>
<body>

    <img class="logo" src="logo.png" width="450" height="110" alt="Random Project">
    <input type="text" name="textbox1" value="" spellcheck="false" dir="ltr" placeholder="Type here" id="textbox1">
    <button id="button1" name="button1" aria-label="Help me" onClick="showAlert();">
        <span id="button1_text">Help me</span>
    </button>
   
    <span class="information">&copy; Copyright DemDevs 2013. All rights reserved. Made by Omar LatrecheDonate now</span>
   
        <span class="tip">Tip: </span><span class="tip_text">The commands are NOT case sensitive</span>
   


</body>
</html>

任何帮助都将不胜感激。

谢谢，奥玛尔！

编辑：

我发现了，我做了两个新的变量：

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var txtValUpper = txtVal.toUpperCase();

和

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var txtValLower = txtVal.toLowerCase();

然后将它们放入代码中，例如：

4

相关讨论

若要对字符串进行不敏感的大小写比较，请先将它们转换为一致的大小写。

1
if ("Foo".toLowerCase() ==="fOo".toLowerCase())
相关讨论

可以将字符串转换为大写并进行比较

1
if(txtVal.toUpperCase() ==="Donate".toUpperCase())

这条线之后

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var txtVal = txtCtrl.value;
txtVal = txtVal.toLowerCase();
相关讨论