Promise.race 的原理

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// race的原理 Promise.race = function(values){     return new Promise((resolve,reject)=>{         for(let i = 0 ; i< values.length;i++){             let current = values[i];             if((typeof current === 'object' &&  current !==null)|| typeof current == 'function'){                 let then = current.then;                 if(typeof then == 'function'){ // 比较哪个promise比较快，谁快用快                     then.call(current,resolve,reject)                 }else{                     resolve(current);                 }             }else{                 resolve(current);             }         }     }); }