解決 nodejs callback無限嵌套（回調地獄）問題

個人比較喜歡的,用co庫的姿勢

測試用函數

function fun1(arg1,arg2,cb){
//dosomthing
cb(null,arg1+"retval"+arg2);
}

function fun2(arg1,cb){
//dosomthing
cb(null,arg1+"retval2");
}

function fun3(arg1,arg2,cb){
//dosomthing
cb(null,arg1+"retval3"+arg2);
}

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正常的nodejs

function testFunNormal(targ1,cb){
fun1(targ1+1,targ1+5,function(err,ret){
if(err){
cb(err);
return;
}
fun2(ret+10,function(err,ret){
if(err){
cb(err);
return;
}
fun3(ret+10,ret+5,function(err,ret){
if(err){
cb(err);
return;
}
cb(null,ret+20);
})
})
})
}

//test normal
testFunNormal(666,function(err,ret){
console.log("err:",err,"ret:",ret);
});
//err: null ret: 667retval67110retval210retval3667retval67110retval2520
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使用 tj大神的co庫後

var co = require("co");

function testCo(targ1,cb){
co(function*(){
let ret = yield (done)=>{fun1(targ1+1,targ1+5,done)};
ret = yield (done)=>{fun2(ret+10,done)};
ret = yield (done)=>{fun3(ret+10,ret+5,done)};
cb(null,ret+20);
}).catch(cb)
}

testCo(666,function(err,ret){
console.log("err:",err,"ret:",ret);
});
//err: null ret: 667retval67110retval210retval3667retval67110retval2520
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是不是感覺天空突然開闊了 ^ ^

附上一些 toy code

"use strict";

const co = require("co");

function sleep(ms) {
return function(done){
setTimeout(function(){
done(0,1111,22222)
}, ms);
}
}

function *work() {
var [rr1,rr2] = yield sleep(60);
console.log("rrr",rr1,rr2);
return "yay";
}

function testCo1(){
co(function *(){
var a = yield work;
var b = yield work;
var c = yield work;

console.log("yay", a);
console.log("yay", b);
console.log("yay" , c);

var res = yield [work, work, work];
console.log(["yay", "yay", "yay"], res);
return "wwwhat"
}).then(function(val){
console.log("aaaa val:",val);
},function(err){
console.log("aaa err:",err);
});

}

function testco2(){
co(function *(){
let ggg = yield function(done){
setTimeout(function(){
done(0,"hahfda");
},1000);
};
console.log("ggg",ggg);
let aaa = yield (done)=>{
setTimeout(()=>{
console.log("aafun ggg:",ggg);
done(null,"ggret");
},1000)
};
console.log("aaaa:",aaa);
return "ret val";
}).then(function(val){
console.log("aaaa val:",val);
},function(err){
console.log("bbbb err:",err);
}).catch(function(err){
console.log("err err:",err);
});
}

function testco3(){

var aa = co(function*(){
console.time("cot");
console.time("111cot");
let ggg = yield function(done){
done(0,"hahfda");
};
console.timeEnd("111cot");
console.log("ggg",ggg);
let aaa = yield (done)=>{
done(null,"ggret");
};
console.log("aaaa:",aaa);
console.timeEnd("cot");
});

console.time("nocot");

function getggg(done){
done(0,"hahfda");
}

getggg(function(err,ggg){
console.log("ggg",ggg);
function getaaa(done){
done(null,"ggret");
}
getaaa(function(err,aaa){
console.log("aaaa:",aaa);
})

return "ret val";
});
console.timeEnd("nocot");

}

function isObj1(val){
return Object == val.constructor;
}
function isObj2(val){
return "object" == typeof val;
}
var obj = {};
console.time("isObj1");
for (let i =0;i<500000;i++){
isObj1(obj);
}
console.timeEnd("isObj1");

console.time("isObj2");
for (let i =0;i<500000;i++){
isObj2(obj);
}
console.timeEnd("isObj2");

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