字符串操作：
//str.length
"micromajor".length // 10 //str.charAt()
"micromajor".charAt(0) // "m"
"micromajor".charAt(100) // "" //str.indexOf()
"micro-major".indexOf("-") // 5
"micro-major-web".indexOf("-") // 5
"micro-major".indexOf("major") // 6
"micromajor".indexOf("-") // -1 //str.search()
"micromajor163".search(/[0-9]/) // 10
"micromajor163".search(/[A-Z]/) // -1 //str.match
"micromajor163".match(/[0-9]/) // ["1"]
"micromajor163".match(/[0-9]/g)// ["1","6","3"]
"micromajor163".match(/[A-Z]/) // null //str.replace(' ',' ');
"micromajor163".replace("163","###") // "micromajor###"
"micromajor163".replace(/[0-9]/,"#") // "micromajor#63"
"micromajor163".replace(/[0-9]/g,"#") // "micromajor###"
"micromajor163".replace(/[0-9]/g,"") // "micromajor" //str.substring
"micromajor".substring(5,7) // "ma"
"micromajor".substring(5) // "major" //str.slice() 可传入负数
"micromajor".slice(5,7) // "ma"
"micromajor".slice(5) // "major"
"micromajor".slice(1,-1) // "icromajo"
"micromajor".slice(-3) // "jor" //str.substr()
"micromajor".substr(5,2) // "ma"
"micromajor".substr(5) // "major" //str.split();
"micro major".split(" ") // ["micro","major"]
"micro major".split(" ",1) // ["micro"]
"micro2major".split(/[0-9]/) // ["micro","major"] //str.toLowerCase();
"MicroMajor".toLowerCase() // "micromajor"
//str.toUpperCase();
"MicroMajor".toUpperCase() // "MICROMAJOR" //字符串拼接
"0571" + "-" + "88888888" // "0571-88888888" //转字符
String(163) // "163"
String(null) // "null" // \转义
"micro\"major" // "micro"major"
"micro\\major" // "micro\major"
"micro\tmajor" // "micro major"
一些正则相关：
var str = 'aaa111bb22c3';
var rex = /[a-z]+([0-9]{3})/; //字符串匹配正则表达式
str.match(rex);
//rex最后不带g,只获取第一个匹配的，且会把字符串中匹配正则表达式中括号内的部分也放到数组中。
// -->['aaa111', '111'];
//带g -->['aaa111']; //测试字符串能否匹配表达式
rex.test(str);// --> true //替换
str.replace(rex,'$1');// --> '111bb22c3'
数组操作：
//arr.indexOf();
var telephones = [110,120,114];
telephones.indexOf(120); // 1
telephones.indexOf(119); // -1 //arr.forEach(function(item,index,array));
var students = [
{id:1,score:80},
{id:2,score:50},
{id:3,score:70}
];
var editScore = function(item,index,array){
item.score += 5;
};
students.forEach(editScore); //arr.reverse();
var students = [
{id:1,score:80},
{id:2,score:50},
{id:3,score:70}
];
students.reverse();
students[0].score; // 70 //arr.sort(function(a,b));
// function(a,b)会返回一个值，如果是小于0的值，就会将a所对应的元素排在前面。
var students = [
{id:1,score:80},
{id:2,score:50},
{id:3,score:70}
];
var byScore = function(a,b){
return b.score-a.score;
};
students.sort(byScore); //arr.sort();
var studentNames = ["wq","xl","gp"];
studentNames.sort();
studentNames; // ["gp","wq","xl"] //arr.push();插到最后一个。
var students = [
{id:1,score:80},
{id:2,score:50},
{id:3,score:70}
];
students.push({id:4,score:90}); var students = [
{id:1,score:80},
{id:2,score:50},
{id:3,score:70}
];
students.push({id:4,score:90},{id:5,score:60}); //arr.unshift;插到第一个。
var students = [
{id:1,score:80},
{id:2,score:50},
{id:3,score:70}
];
students.unshift({id:4,score:90}); //arr.shift();移除第一个并返回移除的值。
var students = [
{id:1,score:80},
{id:2,score:50},
{id:3,score:70}
];
students.shift(); // {id:1,score:80} //arr.pop();移除最后一个并返回移除的值。
var students = [
{id:1,score:80},
{id:2,score:50},
{id:3,score:70}
];
students.pop(); // {id:3,score:70} //arr.splice(移除的元素的索引号，移除的个数，插入的新元素);
var students = [
{id:1,score:80},
{id:2,score:50},
{id:3,score:70}
];
students.splice(1,1,{id:4,score:90}); var students = [
{id:1,score:80},
{id:2,score:50},
{id:3,score:70}
];
students.splice(1,1); var students = [
{id:1,score:80},
{id:2,score:50},
{id:3,score:70}
];
students.splice(1,0,{id:4,score:90}); //arr.slice();
var students = [
{id:1,score:80},
{id:2,score:50},
{id:3,score:70}
];
var newStudents = students.slice(0,2); var students = [
{id:1,score:80},
{id:2,score:50},
{id:3,score:70}
];
var newStudents = students.slice(0); //arr.contat();
var students1 = [
{id:1,score:80},
{id:2,score:50},
{id:3,score:70}
];
var students2 = [
{id:4,score:90},
{id:5,score:60}
];
var students3 = [
{id:6,score:40},
{id:7,score:30}
];
var newStudents = students1.concat(students2,students3); //arr.join();
var emails = ["wq@163.com","gp@163.com","xl@163.com"];
emails.join(";"); // "wq@163.com;gp@163.com;xl@163.com" //arr.forEach();
var scores = [60,70,80,90];
var newScores = [];
var addScore = function(item,index,array){
newScores.push(item+5);
};
scores.forEach(addScore);
newScores; // [65,75,85,95]
console.log(scores.forEach(addScore));
console.log(scores); //arr.map(); 有返回值
var scores = [60,70,80,90];
var addScore = function(item,index,array){
return item+5;
};
scores.map(addScore); // [65,75,85,95] // arr.reduce(function(previousResult,item,index,array),previousResult的初始值);
var students = [
{id:1,score:80},
{id:2,score:50},
{id:3,score:70}
];
var sum = function(previousResult,item,index,array){
console.log(previousResult);
console.log(item);
return previousResult+item.score;
};
students.reduce(sum,0); // 200