Question

我有json数组值，它有年龄和数字。我想创建一个新的数组，其中包含{"num":2}（即）需要返回[{"age":2,"num":2},{"age":3,"num":2}]

＆＃13;

var array_val='[{"age":1,"num":1},{"age":2,"num":2},{"age":3,"num":2}]';
console.log(array_val);
function fetchList(array_val) {
    return array_val = {"num":1};
}
array_val.filter(fetchList)
console.log(array_val);

＆＃13;

Answer 1

您需要使用filter()

var fetched_object = array_val.filter(function(obj) {
  return obj.num == 1;
});

注意：像@NinaScholz一样，你需要JSON.parse字符串，所以它是一个数组。

Answer 2

我在您的代码中看到了2个问题：

您不会将字符串解析为JSON
您的过滤器错误功能

＆＃13;

var array_val='[{"age":1,"num":1},{"age":2,"num":2},{"age":3,"num":2}]';
console.log(array_val);

function fetchList(array_val) {
    return array_val.num === 2;   // return only records whose num is 2
}

// here you parse string into JSON and apply the filter
var data = JSON.parse(array_val).filter(fetchList);

console.log(data);

＆＃13;

Answer 3

你需要解析JSON字符串JSON.parse()。匹配条件错误。num是对象的内在属性。所以你需要匹配a.num == 2。不要忘了添加==

＆＃13;

var array_val='[{"age":1,"num":1},{"age":2,"num":2},{"age":3,"num":2}]';
console.log(array_val);
function fetchList(a) {
    return a.num == 2;
}
var res = JSON.parse(array_val).filter(fetchList)

console.log(res);

＆＃13;

Answer 4

这应该这样做

var array_val=JSON.parse('[{"age":1,"num":1},{"age":2,"num":2},{"age":3,"num":2}]');
console.log(array_val);
function fetchList(array_val) {
    return array_val.num == 2;
}
array_val = array_val.filter(fetchList)
console.log(array_val);

Answer 5

这样可以改为：

var requiredValue = array_val.filter（function（item）{return item.num === 2; }）;

Answer 6

试试这个

var array_val=JSON.parse('[{"age":1,"num":1},{"age":2,"num":2},{"age":3,"num":2}]');
var newarr =[]

for(let i of array_val){
if(i.num == 2){
newarr.push(i);
}

}

console.log(newarr);

获取具有特定值的数组

6 个答案: