Question

如何将对象值数组的每个元素与常数相乘？

输入

[{"key":usd, "value":20 }, {"key":aed, "value":50 },{"inr":usd, "value":30 },{"key":usd, "value":40 }]

输出

[{"key":usd, "value":40 }, {"key":aed, "value":100 },{"inr":usd, "value":60 },{"key":usd, "value":80 }]

Answer 1

const arr = [{"key":"usd", "value":20 }, {"key":"aed", "value":50 },{"inr":"usd", "value":30 },{"key":"usd", "value":40 }];

const modifiedArr = arr.map(item => {
    var modifiedItem = Object.assign({}, item);
    modifiedItem.value *= 2;

    return modifiedItem;
});

console.log(arr);
console.log(modifiedArr);

编辑：如@UncleDave所指出的那样，使用modifiedItem来实现不变性

Answer 2

const arr = [{"key":"usd", "value":20 }, {"key":"aed", "value":50 },{"inr":"usd", "value":30 },{"key":"usd", "value":40 }];
arr.map(function(value,key){
    arr[key].value *=2;
});
console.log(arr);

输出

[{"key":"usd", "value":40 }, {"key":"aed", "value":100 },{"inr":"usd", "value":60 },{"key":"usd", "value":80 }];

Answer 3

不更改原始数组。如果您不理解，请随时发表评论。

let someArray = [{"key":"usd", "value":20 }, {"key":"aed", "value":50 },{"inr":"usd", "value":30 },{"key":"usd", "value":40 }]

let result = someArray.map(data=>{
return {...data, value: data.value*2}
})

console.log(result);

Answer 4

您可以将此示例函数用于此输入类型，否则，您必须更改此函数，将对象作为输入传递：

valueChanger(input){
    var tx = []
    for(var x = 0;x < Object.keys(input).length ; x++){
        var obj = {}
        obj['key'] = input[x]['key'] // do anything with key if you want in here
        obj['value'] = input[x]['value']*2 
        tx.push(obj)
    }
    return tx
}

Answer 5

您可以像这样使用Array.prototype.map()和ES6 arrow syntax：

const arr = [{
  "key": "usd",
  "value": 20
}, {
  "key": "aed",
  "value": 50
}, {
  "inr": "usd",
  "value": 30
}, {
  "key": "usd",
  "value": 40
}];
const value = 2;
const result = arr.map(e => {
  e.value *= value;
  return e;
});
console.log(result);

如果需要，您可以通过返回e.value的doubles值来返回double值：

const arr = [{
  "key": "usd",
  "value": 20
}, {
  "key": "aed",
  "value": 50
}, {
  "inr": "usd",
  "value": 30
}, {
  "key": "usd",
  "value": 40
}];
const value = 2;
const result = arr.map(e => e.value *= value);
console.log(result);

如何将一个常数乘以每个对象值数组？

5 个答案: