JS中数组的不同类型及访问形式，流程中分支不同样式的演示实例

1.JS中数组的不用样式主要有

a.单维数组；

let arr =[“one”,”two”,”three”];

let arr_1 =arr[0];

console.log(arr_1);

// 可以使用foreach循环获取项目中的所有项

arr.forEach(item=>console.log(“this is the:”+item))

// forEach的两个参数

console.log(“forEach具备两个参数”);

arr.forEach((item,key)=>console.log(this is the ${key} numbe系统开发mhkj33r:${item}))

b.多维数组，单维数组中，如果某一项也为数组，那么整体数组即为单维数组

let arrMuliti=[

[“one”,”two”,”three”],

[“first”,”second”,”third”]]

c. 获得数组中的某一项：

let arrMuliti_1 = arrMuliti[0][0]

console.log(arrMuliti_1);

// 可以使用foreach循环获取项目中的所有项

console.log(“以下为循环显示多维数组的各项内容”);

arrMuliti.forEach(item=>item.forEach(subitem=>console.log(subi系统开发mhkj33tem)));

arrMuliti.forEach((item,key)=>item.forEach((subitem,subkey)=>console.log( This is the outside ${key} inside ${subkey} : ${subitem} )));

d.对象数组

console.log(“\n”);

let objectArr = [

{one:1,two:2,three:3},

{first:”1st”,sencond:”2nd”,third:”3rd”},

{chengdu:”成都”,beijing:”北京”,hefei:”合肥”}

];

console.log(obj系统开发mhkj33ectArr[0].one);

e.循环遍历对象数组

console.log(‘——————————‘);

console.log(“遍历对象数组:”);

objectArr.forEach( (item , key )=>console.log(This is the ${key} object:)+” “ + Object.values(item).forEach(items=> console.log( items)))

let obj_2 = {one:”one1”,two:”two2”,three:”three3”};

// 对象的第一种遍历

for(let items in obj_2){

con系统开发mhkj33sole.log(obj_2[items]);

}

console.log(‘————————-‘);

// 对象的第二种遍历

for(let value of Object.values(obj_2)){

console.log(value);

}

console.log(‘—————————————-‘);

2.分支判断的不同类型

// 分支判断主要有

// 1.单分支if

// 2. 双分支 if else

// 3.多分支

// 3.1:if/else if/else

// 3.2.switch/case

// 下面为if else if else 分支,注意 else if是分开写的

let age = 61;

a.系统开发mhkj33单分支

if(age === 60){

console.log(“your age is 60”);

}

console.log(‘——————————————————‘);

b.双分支

if(age ===60){

console.log(‘your age is 60’);

}

else{

console.log(“your age is others”);

}

console.log(“———————————————————“);

双分支简化

console.log(“双分支简化结构”);

age === 60?console.log(“your age is 60”):console.log(“your age i系统开发mhkj33s others”);

console.log(“——————————————————-“);

c.多分支if else if else

if(age < 0 ){

console.log(“your age isn’t right”);

}else if(age < 55){

console.log(“your age is less than 55”);

}else if( age > 70){

console.log(“your age is greater than 70”);

}

else{

console.log(“your age is between 55 and 70”);

}

console.log系统开发mhkj33(‘————————————————-‘);

// switch/case分支

let name = “jiao”;

switch(name){

case “one”:

console.log(“your input is one”);

break;

case “jiao”:

console.log(“your input is right”);

break;

case “two”:

console.log(“your input is two”);

break;

default:

console.log(“please input”);

break;

}