Question

var arr = [{code:'A', number: 1}, {code:'A', number: 2}, {code:'B', number: 3 }]

如何在上面的数组中获得一些具有某些键的对象？

例如，code: 'A'个对象的数量 2 。

如何获得它？

Answer 1

filter将遍历数组并执行您的回调函数。回调函数需要求值为要返回的值的布尔值。

var arr = [{code:'A', number: 1}, {code:'A', number: 2}, {code:'B', number: 3 }]
arr.filter(function(x) { return x.code === 'A'}).length

Answer 2

遍历数组并将诸如count和相应数字之类的信息存储在对象结构中。

＆＃13;

var arr = [{code:'A', number: 1}, {code:'A', number: 2}, {code:'B', number: 3 }];

var obj = {};
debugger;
for (var i =0, len = arr.length; i < len; i += 1) {
  ele = arr[i];
  code = ele.code
  if (!obj[code]) {
    obj[code] = {
      count: 0,
      number: []
    };
  }
  obj[code].count += 1;
  obj[code].number.push(ele.number);
}

function getCount(code) {
  return obj[code].count;
}

console.log(getCount('A')); // 2
console.log(getCount('B')); // 1
console.log(obj);

＆＃13;

获取javascript对象数组中相同键的长度

2 个答案: