jQuery中如何检查字符串以特定字符串开头/结尾（） _前端开发

JavaScript提供了许多字符串方法, 用于检查一个字符串是否为其他字符串的子字符串。因此, jQuery根本不需要执行此任务。但是, 我们将介绍检查字符串是否以字符串开头或结尾的所有不同方法：

startsWith()和endsWith()方法
search()方法
indexOf()方法
substring()方法
substr()方法
slice()方法

让我们考虑一个字符串str ="欢迎使用GEEKS！。现在我们要确定字符串str是否以startword ="欢迎"并以endword =" !!!".
方法：
tartsWith()和endsWith()方法:检查字符串是以特定子字符串开始还是以特定子字符串结束。
例子：

if (str.startsWith(startword) & & str.endsWith(endword)) {// case sensitive console.log( "Yes, The string " + str + " starts with " + startword + " and ends with " + endword); }

search()方法：它检查另一个字符串中是否包含特定字符串, 并返回该子字符串的起始索引。
例子：

if (str.search(startword)==0 & & str.search(endword)==stringlength-endwordlength ) {// case sensitive console.log( "Yes, The string " + str + " starts with " + startword + " and ends with " + endword); }

indexOf()方法：顾名思义, 它在字符串中找到子字符串的起始索引。
例子：

if (str.indexOf(startword)==0 & & str.indexOf(endword)==stringlength-endwordlength) {console.log( "Yes, The string " + str + " starts with " + startword + " and ends with " + endword); }

【jQuery中如何检查字符串以特定字符串开头/结尾（）】substring()方法：它返回起始索引和结束索引之间存在的字符串。
例子：

if (str.substring(0, startwordlength)==startword & & str.substring(stringlength-endwordlength, stringlength)==endword) {console.log( "Yes, The string " + str + " starts with " + startword + " and ends with " + endword); }

substr()方法：它类似于substring()方法, 但以起始索引和子字符串的长度作为参数。
范例：

if (str.substr(0, startwordlength)==startword & & str.substr(stringlength-endwordlength, endwordlength)==endword) {console.log( "Yes, The string " + str + " starts with " + startword + " and ends with " + endword); }

slice()方法：此方法返回字符串中任意两个索引之间的字符串切片。
例子：

if (str.slice(0, startwordlength)==startword & & str.slice(stringlength-endwordlength, stringlength)==endword) {console.log( "Yes, The string " + str + " starts with " + startword + " and ends with " + endword); }

让我们以h1元素中的文本为例, 检查它是否以给定的子字符串开头和结尾。

< !DOCTYPE html> < html> < head> < title> How to know that a string starts/ends with a specific string in jQuery? < /title> < script src= "https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js" > < /script> < /head> < body> < h1 id= "text" > Welcome To GEEKS FOR GEEKS!!! < /h1> < h2> Check whether a word is present in the above sentence < /h2> < input type= "text" id= "startkey" > < input type= "text" id= "endkey" > < button onclick= "MyFunction()" > Check < /button> < h2> startsWith() and endsWith() method < /h2> < h2 id= "startswith" > < /h2> < h2> indexOf() method < /h2> < h2 id= "indexOf" > < /h2> < h2> search() method < /h2> < h2 id= "search" > < /h2> < h2> substring() method < /h2> < h2 id= "substring" > < /h2> < h2> substr() method < /h2> < h2 id= "substr" > < /h2> < h2> slice() method < /h2> < h2 id= "slice" > < /h2> < script> var str = document.getElementById( "text" ).innerText; stringlength = str.length; var startword = "" ; var endword = "" ; function MyFunction() { startword = document.getElementById( "startkey" ).value; endword = document.getElementById( "endkey" ).value; console.log(startword); console.log(endword) startwordlength = startword.length; endwordlength = endword.length; if (str.startsWith(startword) & & str.endsWith(endword)) { // case sensitive var h2 = document.getElementById( "startswith" ); h2.innerHTML = "Yes, The string " + str + " starts with " + startword + " and ends with " + endword; } else { var h2 = document.getElementById( "startswith" ); h2.innerHTML = "No, The string " + str + " doesn't start and endwith the given words" ; } //Js if (str.indexOf(startword) == 0 & & str.indexOf( endword) == stringlength - endwordlength) { var h2 = document.getElementById( "indexOf" ); h2.innerHTML = "Yes, The string " + str + " starts with " + startword + " and ends with " + endword; } else { var h2 = document.getElementById( "indexOf" ); h2.innerHTML = "No, The string " + str + " doesn't start and endwith the given words" ; } //Js if (str.search( startword) == 0 & & str.search(endword) == stringlength - endwordlength) {// case sensitive var h2 = document.getElementById( "search" ); h2.innerHTML = "Yes, The string " + str + " starts with " + startword + " and ends with " + endword; } else { var h2 = document.getElementById( "search" ); h2.innerHTML = "No, The string " + str + " doesn't start and endwith the given words" ; } //Js if (str.substring( 0, startwordlength) == startword & & str.substring( stringlength - endwordlength, stringlength) == endword) { var h2 = document.getElementById( "substring" ); h2.innerHTML = "Yes, The string " + str + " starts with " + startword + " and ends with " + endword; } else { var h2 = document.getElementById( "substring" ); h2.innerHTML = "No, The string " + str + " doesn't start and endwith the given words" ; }if (str.substr( 0, startwordlength) == startword & & str.substr( stringlength - endwordlength, endwordlength) == endword) { var h2 = document.getElementById( "substr" ); h2.innerHTML = "Yes, The string " + str + " starts with " + startword + " and ends with " + endword; } else { var h2 = document.getElementById( "substr" ); h2.innerHTML = "No, The string " + str + " doesn't start and endwith the given words" ; } if (str.slice( 0, startwordlength) == startword & & str.slice( stringlength - endwordlength, stringlength) == endword) { var h2 = document.getElementById( "slice" ); h2.innerHTML = "Yes, The string " + str + " starts with " + startword + " and ends with " + endword; } else { var h2 = document.getElementById( "slice" ); h2.innerHTML = "No, The string " + str + " doesn't start and endwith the given words" ; } } < /script> < /body> < /html>

输出如下：