10、使用 indexOf() 检查元素是否存在 JavaScript 为我们提供了内置方法 indexOf()。 这个方法让我们可以方便地检查某个元素是否存在于数组中。 indexOf() 方法接受一个元素作为输入参数,并返回该元素在数组中的位置(索引);若该元素不存在于数组中则返回 -1。 function quickCheck(arr, elem) { return arr.index...
string-in-js npm package The string-in-js npm package provides string manipulation functions designed to enhance JavaScript's built-in string capabilities. It provides a set of intuitive functions that allow you to easily transform and manipulate strings in various ways. ...
constnullVar=null;nullVar.toString();// TypeError: nullVar is nullString(nullVar);// "null"constundefinedVar=undefined;undefinedVar.toString();// TypeError: undefinedVar is undefinedString(undefinedVar);// "undefined" Specification ECMAScript Language Specification ...
In JavaScript, indexOf() is a string method that is used to find the location of a substring in a string. Because the indexOf() method is a method of the String object, it must be invoked through a particular instance of the String class.Syntax...
indexOf()Returns the index (position) of the first occurrence of a value in a string lastIndexOf()Returns the index (position) of the last occurrence of a value in a string lengthReturns the length of a string localeCompare()Compares two strings in the current locale ...
This JavaScript tutorial explains how to use the string method called lastIndexOf() with syntax and examples. In JavaScript, lastIndexOf() is a string method that is used to find the location of a substring in a string, searching the string backwards.
text.indexOf("a"); Try it Yourself » Description TheindexOf()method returns the position of the first occurrence of a value in a string. TheindexOf()method returns -1 if the value is not found. TheindexOf()method is case sensitive. ...
String对象(*) length属性:获取字符串的字符个数。(无论中文字符还是英文字符都算1个字符。) charAt(index)方法:获取指定索引位置的字符。(索引从0开始) indexOf(‘字符串’,startIndex)方法:获取指定字符串第一次出现的位置。startIndex表示从第几
findByteIndex(Integer charIndex)- Finds the byte index for the given character index in the string. Note: a "byte index" is really a "JavaScript string index", not a true byte offset. Use this function to convert a UTF character boundary to a JavaScript string index. ...