当用户在文本框中键入时，我希望它用小数格式化自己。
例如，如果用户键入 10000，我希望它在他键入时显示为 10,000。
【问题讨论】：
DisplayFormat 属性。
标签： javascript c# asp.net
给你。处理退格/删除使其特别具有挑战性。那很有趣！ :-)
我已将此添加到我的在线脚本组合中，地址为 rack.pub。
function toast(a,b){b||(b=2750);var c={message:a,timeout:b};snackbarContainer.MaterialSnackbar.showSnackbar(c)}var doc=document,textArea=doc.getElementById("area"),numArray=[],backArray=[],num="",numF="",regx="",thisChar="",lastChar="",str="",index=0;window.snackbarContainer=doc.querySelector("#toast"),textArea.addEventListener("keydown",function(){var a=event.keyCode;if(str=this.value,(8==a||46==a)&&(backArray=[],index=str.length-1,lastChar=str.charAt(index),!isNaN(lastChar)||","==lastChar))for(var b=str.length-1;b>=0;b--){if(" "==str.charAt(b))return;if(isNaN(str.charAt(b))&&","!=str.charAt(b))return;backArray.push(str.charAt(b))}if(32==a&&backArray[1]){var c=backArray.reverse().slice(0,-1).join(""),d=c.replace(/\,/g,""),e=Number(d).toLocaleString().toString(),f=str.lastIndexOf(c);f>=0&&f+c.length>=str.length&&(str=str.substring(0,f)+e),this.value=str}}),textArea.addEventListener("keypress",function(){if(thisChar=this.value.slice(-1),isNaN(thisChar)){num=numArray.join(""),numArray=[],numF=Number(num).toLocaleString().toString(),regx=num+"(?!.*"+num+")",regx=new RegExp(regx);var a=this.value.replace(regx,numF);this.value=a}else{if(" "==thisChar){num=numArray.join(""),numArray=[],numF=Number(num).toLocaleString().toString(),regx=num+"(?!.*"+num+")",regx=new RegExp(regx);var a=this.value.replace(regx,numF);return void(this.value=a)}numArray.push(thisChar)}}); html body {
font-family: 'Roboto', sans-serif;
background: #f5f5f5;
}
.text-right{
text-align:right;
}
.text-center{
text-align:center;
}
.text-left{
text-align:left;
}
.thin{
font-weight: 100;
}
.heading{
font-size:3em;
}
.subtitle{
margin-top: -16px;
}
#submit{
margin-top:10px;
} <link rel="stylesheet" href="https://fonts.googleapis.com/icon?family=Material+Icons">
<link rel="stylesheet" href="https://code.getmdl.io/1.2.0/material.indigo-pink.min.css">
<link href="https://fonts.googleapis.com/css?family=Roboto:100,400" rel="stylesheet">
<div class="demo-layout-transparent mdl-layout mdl-js-layout">
<main class="mdl-layout__content page-content">
<section class="mdl-grid">
<div class="mdl-layout-spacer"></div>
<div class="mdl-cell mdl-cell--4-col">
<h1 class="mdl-color-text--indigo-900 text-right thin">commas.js demo</h1>
<h6 class="mdl-color-text--indigo-500 text-right subtitle">
JavaScript to automatically add commas to numbers in a text area
</h6>
</div>
<div class="mdl-layout-spacer"></div>
</section>
<section class="mdl-grid">
<div class="mdl-layout-spacer"></div>
<div class="mdl-cell mdl-cell--4-col">
<h6 class="mdl-color-text--black thin">
Basically it auto formats numbers as you type in the text area. Give it a try.
</h6>
</div>
<div class="mdl-layout-spacer"></div>
</section>
<section class="mdl-grid">
<div class="mdl-layout-spacer"></div>
<div class="mdl-textfield mdl-js-textfield mdl-cell mdl-cell--4-col">
<textarea class="mdl-textfield__input" type="text" rows= "3" id="area" ></textarea>
<label class="mdl-textfield__label" for="area">Type Here...</label>
</div>
<div class="mdl-layout-spacer"></div>
</section>
</main>
</div>
<!-- IE Compatibility shims DO NOT DELETE-->
<!--[if lt IE 9]>
<script src="//cdnjs.cloudflare.com/ajax/libs/html5shiv/3.7.2/html5shiv.min.js""></script>
<![endif]-->
<!--[if IE]>
<script src="//cdnjs.cloudflare.com/ajax/libs/es5-shim/4.1.7/es5-shim.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/classlist/2014.01.31/classList.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/selectivizr/1.0.2/selectivizr-min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/flexie/1.0.3/flexie.min.js"></script>
<link href="../assets/ie.css" rel="stylesheet">
<![endif]-->
<!-- end shims -->
<script defer src="https://code.getmdl.io/1.2.0/material.min.js"></script>【讨论】：
使用替换和正则表达式，然后在 keyup 上排队。
$(selector).replace(/(\d)(?=(\d\d\d)+(?!\d))/g, "$1,")
//will replace with commas
【讨论】：
事实证明，这个问题比我预期的更具挑战性（我应该更清楚）。这是我得到的，使用 vanilla Javascript。
您可以为 TextBox 的onkeyup 事件设置事件处理程序：
<asp:TextBox ID="txtAutoFormat" runat="server" onkeyup="processKeyUp(this, event)" />
这里是 Javascript 代码：
<script type="text/javascript">
function extractDigits(str) {
return str.replace(/\D/g, '');
};
function findDigitPosition(str, index) {
var pos = 0;
for (var i = 0; i < str.length; i++) {
if (/\d/.test(str[i])) {
pos += 1;
if (pos == index) {
return i + 1;
}
}
}
};
function isCharacterKey(keyCode) {
// Exclude arrow keys that move the caret
return !(35 <= keyCode && keyCode <= 40);
};
function processKeyUp(txt, e) {
if (isCharacterKey(e.keyCode)) {
var value = txt.value;
// Save the selected text range
var start = txt.selectionStart;
var end = txt.selectionEnd;
var startDigit = extractDigits(value.substring(0, start)).length;
var endDigit = extractDigits(value.substring(0, end)).length;
// Insert the thousand separators
txt.value = extractDigits(value).replace(/(\d{1,3}|\G\d{3})(?=(?:\d{3})+(?!\d))/g, "$1,");
// Restore the adjusted selected text range
txt.setSelectionRange(findDigitPosition(txt.value, startDigit), findDigitPosition(txt.value, endDigit));
}
};
</script>
致谢：
CMS从Regex using javascript to return just numbers中的字符串中提取数字的解决方案。
Alan Moore 在How do I add thousand separators with reg ex? 中插入千位分隔符的正则表达式。
注意： Ron Royston 使用toLocaleString 的想法也很有趣。它可以提供更通用的解决方案。你可以替换processKeyUp这行：
txt.value = extractDigits(value).replace(/(\d{1,3}|\G\d{3})(?=(?:\d{3})+(?!\d))/g, "$1,");
以下内容：
txt.value = Number(extractNumber(value)).toLocaleString();
【讨论】：
尝试输入掩码，这是一个示例： http://digitalbush.com/projects/masked-input-plugin/
【讨论】：
【讨论】：