从对象中删除默认值 [英] remove default values from an object

问题描述

我有两个javascript对象：

I have two javascript objects:

var a = {
    x: 1, 
    y: {
        faz: 'hello', 
        baz: ''
    },
    z: [1, 2]
};


var defaults = {
    x: 2,
    y: {
        faz: '', 
        baz: ''
    },
    z: [1, 2]
};

我想只保留的字段默认情况下不同：

I want to only keep the fields of a that are different from the default:

a = remove_defaults(a, defaults); // <---- i need this fnc
{
    x: 1,
    y: {
        faz: 'hello'
    }
}

目标是从作为状态的对象中删除默认值（通过URL）。状态可以有嵌套字段，因此浅层比较是不够的。叶子值都是原始的（数字，字符串，bool）。

The goal is to remove default values from an object that serves as a state (via URL). The state can have nested fields, so a shallow compare is not enough. The leaf values are all primitive (number, string, bool).

（这有点像 undercore.js的反面's _。默认值（）方法）

(this is a bit like the opposite of underscore.js's _.defaults() method)

什么是实现这个目标的最佳方法是？

What is the best way to achieve this?

解决方案可以使用 underscore.js 如果有帮助，但没有 jquery 。

The solution can use underscore.js if that helps, but no jquery.

推荐答案

尝试这个：

function removeDuplicates(a, defaults, result) {
  for (var i in a) {
    if (i in defaults) {
      if (typeof a[i] == "object" 
          && typeof defaults[i] == "object"
          && Object.prototype.toString.call(defaults[i]) !== '[object Array]') {
        result[i] = removeDuplicates(a[i], defaults[i], {});
      } else if (a[i] !== defaults[i]) {
        result[i] = a[i];  
      }
    } else {
      result[i] = a[i];
    }
  }

  return result;
}


var result = removeDuplicates(a, defaults, {});

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