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The () [] {} of a regular expression has different meanings.

() is to extract the matching string. If there are several () in the expression, there are several matching strings.

(\ s*) A string that represents consecutive spaces.

[] is the range of characters that define a match. For example, [a-zA-Z0-9] means that the characters in the corresponding position should match English characters and numbers. [\ s*] indicates a space or a * sign.

{} is generally used to indicate the length of a match, for example,\ s {3} means to match three spaces, and\ s [1pr 3] means to match one to three spaces.

(0-9) match'0-9 'itself. [0-9] * matching numbers (note that there is a *, which can be empty) [0-9] + matching numbers (note that there is a + after it, which cannot be empty) {1-9} spelling error.

[0-9] {0jue 9} represents a numeric string of length from 0 to 9.

/ / to clear the spaces on both sides of the JS, you need to write your own rules. In JQ, you can directly call $.trim (str) to remove the spaces before and after the string String.prototype.trim = function () {return this.replace (/ (^\ s *) | (\ sblank $) / g,'');}; / / merge multiple whitespace into one blank String.prototype.ResetBlank = function () {var regEx = /\ blank _ g Return this.replace (regEx,'');}; / / reserved digits String.prototype.GetNum = function () {var regEx = / [^\ d] / g; return this.replace (regEx,'');}; / / reserved Chinese String.prototype.GetCN = function () {var regEx = / [^\ u4e00 -\ u9fa5\ uf900-\ ufa2d] / g; return this.replace (regEx,'');} / / String is converted to Number String.prototype.ToInt = function () {return isNaN (parseInt (this))? This.toString (): parseInt (this);}; / / get the byte length String.prototype.GetLen = function () {var regEx = / ^ [\ u4e00 -\ u9fa5\ uf900-\ ufa2d] + $/; if (regEx.test (this)) {return this.length * 2;} else {var oMatches = this.match (/ [\ x00 -\ xff] / g); var oLength = this.length * 2-oMatches.length; return oLength;}} / / get the full name of the file String.prototype.GetFileName = function () {var regEx = / ^. * / ([^\ /\?] *). * $/; return this.replace (regEx,'$1');}; / / get the file extension String.prototype.GetExtensionName = function () {var regEx = / ^. / [^\ /] * (\. [^\.\?] *). * $/; return this.replace (regEx,'$1') }; / / replace all String.prototype.replaceAll = function (reallyDo, replaceWith, ignoreCase) {if (! RegExp.prototype.isPrototypeOf (reallyDo)) {return this.replace (new RegExp (reallyDo, (ignoreCase?) "gi": "g"), replaceWith);} else {return this.replace (reallyDo, replaceWith);}}; / / format string add By Liu Jingning 2010-12-09 String.Format = function () {if (arguments.length = = 0) {return';} if (arguments.length = = 1) {return arguments [0];} var reg = / {(\ d+)?} / g; var args = arguments Var result = arguments [0] .replace (reg, function ($0, $1) {return args [parseInt ($1) + 1];}); return result;}; / / numeric zero padding Number.prototype.LenWithZero = function (oCount) {var strText = this.toString (); while (strText.length

< oCount) { strText = '0' + strText; } return strText; }; // Unicode还原 Number.prototype.ChrW = function() { return String.fromCharCode(this); }; // 数字数组由小到大排序 Array.prototype.Min2Max = function() { var oValue; for (var i = 0; i < this.length; i++) { for (var j = 0; j oValue) { oValue = this[i]; } } return oValue; }; // 获得数字数组中最小项 Array.prototype.GetMin = function() { var oValue = 0; for (var i = 0; i < this.length; i++) { if (this[i] < oValue) { oValue = this[i]; } } return oValue; }; // 获取当前时间的中文形式 Date.prototype.GetCNDate = function() { var oDateText = ''; oDateText += this.getFullYear().LenWithZero(4) + new Number(24180).ChrW(); oDateText += this.getMonth().LenWithZero(2) + new Number(26376).ChrW(); oDateText += this.getDate().LenWithZero(2) + new Number(26085).ChrW(); oDateText += this.getHours().LenWithZero(2) + new Number(26102).ChrW(); oDateText += this.getMinutes().LenWithZero(2) + new Number(20998).ChrW(); oDateText += this.getSeconds().LenWithZero(2) + new Number(31186).ChrW(); oDateText += new Number(32).ChrW() + new Number(32).ChrW() + new Number(26143).ChrW() + new Number(26399).ChrW() + new String('26085199682010819977222352011620845').substr(this.getDay() * 5, 5).ToInt().ChrW(); return oDateText; }; //扩展Date格式化 Date.prototype.Format = function(format) { var o = { "M+": this.getMonth() + 1, //月份 "d+": this.getDate(), //日 "h+": this.getHours() % 12 == 0 ? 12 : this.getHours() % 12, //小时 "H+": this.getHours(), //小时 "m+": this.getMinutes(), //分 "s+": this.getSeconds(), //秒 "q+": Math.floor((this.getMonth() + 3) / 3), //季度 "S": this.getMilliseconds() //毫秒 }; var week = { "0": "\u65e5", "1": "\u4e00", "2": "\u4e8c", "3": "\u4e09", "4": "\u56db", "5": "\u4e94", "6": "\u516d" }; if (/(y+)/.test(format)) { format = format.replace(RegExp.$1, (this.getFullYear() + "").substr(4 - RegExp.$1.length)); } if (/(E+)/.test(format)) { format = format.replace(RegExp.$1, ((RegExp.$1.length >

1)? (RegExp.$1.length > 2? "\ u661f\ u671f": "):") + week [this.getDay () + "]);} for (var k in o) {if (new RegExp (" ("+ k +") ") .test (format)) {format = format.replace (RegExp.$1, (RegExp.$1.length = = 1)? (O [k]): ("00" + o [k]) .substr (("" + o [k]) .length));}} return format;} Date.prototype.Diff = function (interval, objDate) {/ / if the parameter is insufficient or objDate is not a date type, return undefined if (arguments.length < 2 | | objDate.constructor! = Date) {return undefined } switch (interval) {/ / calculate second difference case 's': return parseInt ((objDate-this) / 1000); / / calculate difference case' n': return parseInt ((objDate-this) / 60000); / / calculate time difference case 'h': return parseInt ((objDate-this) / 3600000); / / calculate diurnal difference case' d': return parseInt ((objDate-this) / 86400000) / / calculate weekly difference case 'w': return parseInt ((objDate-this) / (86400000 * 7)); / / calculate monthly difference case'mm: return (objDate.getMonth () + 1) + ((objDate.getFullYear ()-this.getFullYear ()) * 12)-(this.getMonth () + 1); / / calculate annual difference case'yearly: return objDate.getFullYear ()-this.getFullYear (); / / input error default: return undefined }}; / / check whether Object.prototype.IsNullOrEmpty = function () {var obj = this; var flag = false; if (obj = = null | | obj = = undefined | | typeof (obj) = = 'undefined' | | obj = =') {flag = true;} else if (typeof (obj) = = 'string') {obj = obj.trim (); if (obj = =') {/ / empty flag = true } else {/ / is not empty obj = obj.toUpperCase (); if (obj = = 'NULL' | | obj = =' UNDEFINED' | | obj = ='{}') {flag = true;}} else {flag = false;} return flag; Thank you for reading! This is the end of this article on "sample Analysis of regular expressions in JS". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, you can share it for more people to see!

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