JavaScript is an essential language for web development, and understanding its core features and methods is crucial for every developer. One such method is the indexOf() method, which can be highly useful when
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方法/步骤 1 在桌面右键，新建-》文本文档 2 重命名文档为：abc.html（这里扩展名也要修改）3 右键点击abc.html-》打开方式-》记事本，输入<!DOCTYPE html>indexOffunction funstr(){var str="dasdasdadada";var str1=str.substr(2,5);alert(str1);保存-》关闭文档，在桌面双击打开，就能看到效果。注意...
let str = "Hello World!";let pos = str.indexOf(/W[a-z]*/);console.log(pos); // 6 五、注意事项 1、indexOf() 方法区分大小写。例如，如果要查找的文本为"world"，而实际字符串中为"World"，则返回-1。2、indexOf() 方法返回第一个匹配的位置。如果要查找所有匹配的位置，则需要使用正则表达...
There are 3 methods for extracting a part of a string: slice(start, end) substring(start, end) substr(start, length) The slice() Method slice()extracts a part of a string and returns the extracted part in a new string. The method takes 2 parameters: the starting index (position), and...
JavaScript操作字符串常用方法 一 查询操作 indexOf和lastIndexOf: 查找字符串是否包含某个字符(串),查找到则返回该字符(串)索引号,否则返回 -1,区分大小写;前者是从前往后查,后者是从后往前查 let str = 'javascript vue react'; // indexOf: 查找字符串是否包含某个字符,查找到则返回索引号,否则返回 -1 ...
The stringindexOf()method returns the index of the first occurence of the substring in a string. Example constmessage ="JavaScript is not Java"; // returns index of 'v' in first occurrence of 'va'constindex = message.indexOf("va"); ...
可以使用String作为toString()更可靠的代替方法,因为它在用于null和undefined时仍然有效。例如: js constnullVar=null;nullVar.toString();// TypeError: nullVar is nullString(nullVar);// "null"constundefinedVar=undefined;undefinedVar.toString();// TypeError: undefinedVar is undefinedString(undefinedVar);/...
返回JavaScript String 对象参考手册(目录) 定义和用法 indexOf() 方法可返回某个指定的字符串值在字符串中首次出现的位置。 语法 stringObject.indexOf(searchvalue,fromindex) 1. 说明 该方法将从头到尾地检索字符串 stringObject,看它是否含有子串 searchvalue。开始检索的位置在字符串的 fromindex 处或字符串的开...
Well organized and easy to understand Web building tutorials with lots of examples of how to use HTML, CSS, JavaScript, SQL, Python, PHP, Bootstrap, Java, XML and more.