Question

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如何编写let locArr = [{ x: 0, y: 0 }, { x: 2, y: 4 }, { x: 6, y: 8 }]; // my asynchronous function that returns a promise function findLoc(x, y) { return new Promise((resolve, reject) => { let a = setTimeout(() => { resolve({ x: x * x, y: y * y }); }, 500); }); } Promise.all([ // my problem is below findLoc(locArr[0].x, locArr[0].y), findLoc(locArr[1].x, locArr[1].y), findLoc(locArr[2].x, locArr[2].y), ]).then(values => { // all values from all the promises });函数从不同大小的数组中获取参数？

我想将参数传递给Promise.all()类的.all()方法中接受的promise数组。最好的方法是什么？

Answer 1

使用map代替

let locArr = [{
  x: 0,
  y: 0
}, {
  x: 2,
  y: 4
}, {
  x: 6,
  y: 8
}];

// my asynchronous function that returns a promise
function findLoc(x, y) {
  return new Promise((resolve, reject) => {
    let a = setTimeout(() => {
      resolve({
        x: x * x,
        y: y * y
      });
    }, 500);
  });
}

Promise.all(
  locArr.map(o => findLoc(o.x, o.y))
).then(values => {
  // all values from all the promises
  console.log(values)
});

Answer 2

您可以使用map：

let locArr = [{ x: 0, y: 0 }, { x: 2, y: 4 }, { x: 6, y: 8 }];

// my asynchronous function that returns a promise
function findLoc(x, y) {
    return new Promise((resolve, reject) => {
        let a = setTimeout(() => {
            resolve({ x: x * x, y: y * y });
        }, 500);
    });
}

Promise.all(
  locArr.map(//map location to promise
    location=>findLoc(location.x,location.y)
  )
).then(values => {
    // all values from all the promises
});

Answer 3

这是一个需要稍微修改let locArr = [{ x: 0, y: 0 }, { x: 2, y: 4 }, { x: 6, y: 8 }]; // my asynchronous function that returns a promise // function findLoc({x, y}) { return new Promise((resolve, reject) => { let a = setTimeout(() => { resolve({ x: x * x, y: y * y }); }, 500); }); } Promise.all(locArr.map(findLoc)).then(values => { console.log(values); });的输入的技巧：

 var someArray = [1,0,1,1,1,1,0,0,1,0,1,0,0,1,0,1,0,1,1,1,1,0,1,1,0,1,0]; 

 function simpleForLoop(array){
   var numArgs = someArray.length;
   for(var loop = 0; loop < numArgs; loop++){
    var arg = someArray[loop];
    if(arg  !== 0 && arg !== 1){ return false; }
   }
   return true;
  }

  var isbool = simpleForLoop(someArray);

Answer 4

使用map，就像其他人说的那样，但也调整findLoc()函数以获得最简单的读数：

let locArr = [{ x: 0, y: 0 }, { x: 2, y: 4 }, { x: 6, y: 8 }];

// my asynchronous function that returns a promise
function findLoc(coordinates) {
    return new Promise((resolve, reject) => {
        let a = setTimeout(() => {
            resolve({ 
              x: coordinates.x * coordinates.x, 
              y: coordinates.y * coordinates.y 
            });
        }, 500);
    });
}

Promise
    .all(locArr.map(findLoc))
    .then(values => {
        console.log(JSON.stringify(values, false, 2));
    });

如何在承担参数的promises数组上使用Promise.all（）？

4 个答案: