stackoverflow/async-iterator.js at main · javascript-2020/stackoverflow · GitHub

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(async()=>{
console.clear();


//data source

    var i=0;
    var arr=[1,2,3];

    setTimeout(fn,1000);

    function fn(){

          if(i==3){
                end();
          }else{
                read(arr[i++]);
                setTimeout(fn,1000);
          }

    }//fn


    function read(value){

          iterator.resolve({value});

    }//read

    function end(){

          iterator.resolve({done:true});

    }//end


    var iterator    = asyncIterator();
    function asyncIterator(){

          var iterator        = ()=>{return {next:()=>new Promise(res=>iterator.resolve=res)}};
          iterator.resolve    = null;
          return iterator;

    }//asynciterator


    var a = {};
    a[Symbol.asyncIterator]   = iterator;


    for await(let x of a){

        console.log(x)

    }//for


})();