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js控制異步輸出順序

JavaScript

哈士奇WWW 2019-08-05 23:02:27

classTest{constructor(){constnums=[1,2,3];(async()=>{for(letiofnums){letx=awaitthis.print(i);console.log(x);}})();}print(x){returnnewPromise((resolve,reject)=>{setTimeout(()=>{resolve(x);},1000);})}}consttest=newTest();(async()=>{letx4=awaittest.print(4);console.log(x4);letx5=awaittest.print(5);console.log(x5);})();怎樣才能做到順序輸出12345？

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2 回答

互換的青春

TA貢獻(xiàn)1797條經(jīng)驗(yàn) 獲得超6個(gè)贊

Test類增加一個(gè)cprm屬性，用來(lái)接收構(gòu)造函數(shù)里面的異步調(diào)用，值是Promise類型。然后在調(diào)用輸出4之前await這個(gè)cprm屬性，就可以等到構(gòu)造函數(shù)的123都輸出完成后再輸出4。classTest{constructor(){constnums=[1,2,3];this.cprm=(async()=>{for(letiofnums){letx=awaitthis.print(i);console.log(x);}})();}print(x){returnnewPromise((resolve,reject)=>{setTimeout(()=>{resolve(x);},1000);})}}consttest=newTest();(async()=>{awaittest.cprm;letx4=awaittest.print(4);console.log(x4);letx5=awaittest.print(5);console.log(x5);})();

反對(duì) 回復(fù) 2019-08-05

蝴蝶刀刀

TA貢獻(xiàn)1801條經(jīng)驗(yàn) 獲得超8個(gè)贊

classTest{constructor(){constnums=[1,2,3];this.init=Promise.all(nums.map(asyncn=>console.log(awaitthis.print(n,true))));}print(x,isInit=false){return(isInit?Promise.resolve():this.init).then(()=>newPromise((resolve,reject)=>{setTimeout(()=>{resolve(x);},1000);}));}}consttest=newTest();(async()=>{letx4=awaittest.print(4);console.log(x4);letx5=awaittest.print(5);console.log(x5);})();}