jk node笔记（1）

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npm init 把普通的项目目录变成npm包
npm install glob 安装glob依赖，项目转移时可以把node_modules删除后再转移
rm -rf node_modules 删除node_modules
npm install 读取项目中package.json中的依赖目录，安装node_modules

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// 回调函数
function interview(callback){
    setTimeout(()=>{
        var num=Math.random();
        console.log(num);
        if(num<0.5){
            callback('succ')
        }else{
            callback(new Error('fail'))
        }
    },500)
}
try{
    interview(function(res){
        if(res instanceof Error){
            return console.log('cry');
        }
        console.log('smile')
    }) 
}catch{

}

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//Promise
//例一
function interview() {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            var num = Math.random();
            console.log(num);
            if (num < 0.5) {
                resolve('succ')
            } else {
                reject(new Error('fail'))
            }
        }, 1000)
    })
}

var promise = interview();
promise.then(
    (res) => {
        console.log('smile')
    }
).catch(
    (err) => {
        console.log('cry')
    }
)

//Promise
//例二
function interview(round) {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            var num = Math.random();
            console.log(num);
            if (num < 0.5) {
                resolve('succ')
            } else {
                var error=new Error('fail');
                error.round=round;
                reject(error);
            }
        }, 1000)
    })
}

var promise=interview(1)
    .then(()=>{
        return interview(2)
    })
    .then(()=>{
        return interview(3)
    })
    .then(()=>{
        console.log('smile');
    })
    .catch((err)=>{
        console.log('cry at '+err.round+' round')
    })

//Promise
//例三
function interview(name) {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            var num = Math.random();
            console.log(num);
            if (num < 0.5) {
                resolve('succ')
            } else {
                var error = new Error('fail');
                error.name = name;
                reject(error);
            }
        }, 1000)
    })
}

Promise.all([
    interview('geekbang'),
    interview('tencent')
]).then(() => {
    console.log('smile');
})
    .catch((err) => {
        console.log('cry at ' + err.name)
    })

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//async、await
function interview(round) {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            var num = Math.random();
            console.log(num);
            if (num < 0.5) {
                resolve('succ')
            } else {
                var error=new Error('fail');
                error.round=round;
                reject(error);
            }
        }, 1000)
    })
}

(async function(){
    try{
        // await interview(1);
        // await interview(2);
        // await interview(3);
        await Promise.all([interview(1),interview(2)])
    }catch(e){
        return console.log('cry at '+e.round+' round');
    }
    console.log('smile');
})()