字符串的基礎(chǔ)
1.字符串的表示''或""包含的
var answer = "It's alright";
var answer = "He is called 'Johnny'";
var answer = 'He is called "Johnny"';
2.字符串的長(zhǎng)度length
var txt = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
var sln = txt.length;
3.字符串中常用的轉(zhuǎn)義字符\
var x = 'It\'s alright'; //It's alright
var y = "We are the so-called \"Vikings\" from the north." //We are the so-called "Vikings" from the north.
4.字符串的拼接+與concat()
var text = "Hello" + " " + "World!"; //Hello World!
var text = "Hello".concat(" ", "World!"); //Hello World!
5.字符串string轉(zhuǎn)換為對(duì)象object
var x = "John";
var y = new String("John");
// typeof x will return string
// typeof y will return object
不要使用這種string創(chuàng)建object，它會(huì)使代碼執(zhí)行速度變慢，使代碼更復(fù)雜化。
字符串的方法
1.返回指定索引區(qū)間的子串substring(start,end)與slice()類似，但不能取負(fù)值
var s = 'hello, world'
s.substring(0, 5); // 從索引0開始到5（不包括5），返回hello
s.substring(7); // 從索引7開始到結(jié)束，返回world
s.slice(-5) ; //從d:-1開始到w:-5,返回hello
2.返回指定長(zhǎng)度區(qū)間的子串substr(start,length)與slice()類似，但不能取負(fù)值
var s = 'hello, world'
s.substr(0,5); //從索引0開始截取的長(zhǎng)度為5，返回hello
3.內(nèi)容的替換replace()
str = "Please visit Microsoft!";
var n = str.replace("Microsoft", "W3Schools"); //Please visit W3Schools
4.要替換不區(qū)分大小寫的，請(qǐng)使用帶i標(biāo)志（不敏感）的正則表達(dá)式
str = "Please visit Microsoft!";
var n = str.replace(/MICROSOFT/i, "W3Schools"); //Please visit W3Schools
5.若要替換所有匹配項(xiàng)，請(qǐng)使用一個(gè)正則表達(dá)式g（全局匹配）
str = "Please visit Microsoft and Microsoft!";
var n = str.replace(/Microsoft/g, "W3Schools"); //Please visit W3Schools and W3Schools
6.把一個(gè)字符串全部變?yōu)榇髮?code>toUpperCase()
var s = 'Hello';
s.toUpperCase(); // 返回HELLO
7.把一個(gè)字符串全部變?yōu)樾?code>toLowerCase()
var s = 'Hello';
var lower = s.toLowerCase(); // 返回'hello'并賦值給變量lower
lower; // 'hello'
8.字符串的查找arr[]與charAt()
var str = "HELLO WORLD";
str[0]; // returns H
var str = "HELLO WORLD";
str.charAt(0); // returns H
