javascript - 如何跳过相同的值并获取数组长度

Question

我有我的示例数组:

var person = [{
    firstName:"John",
    lastName:"Doe",
    age:46
},
{
    firstName:"Alexander",
    lastName:"Bru",
    age:46
},
{
    firstName:"Alex",
    lastName:"Bruce",
    age:26
}];

简单 person.length 给我数组的长度，但我需要在年龄相同时合并值。因此，如果两个人的年龄相同，则返回 1 而非 2。抱歉我的英语不好，我可能会犯错误。

Answer 1

使用 Array#forEach 带有年龄对象引用的方法。

var person = [{
  firstName: "John",
  lastName: "Doe",
  age: 46
}, {
  firstName: "Alexander",
  lastName: "Bru",
  age: 46
}, {
  firstName: "Alex",
  lastName: "Bruce",
  age: 26
}];
// object for storing reference to age
var obj = {},
  res = 0;
// iterate and count
person.forEach(function(v) {
  // check age already not defined
  if (!obj[v.age]) {
    // define the property
    obj[v.age] = true;
    // increment count
    res++;
  }
});

console.log(res);