javascript 将 2 个对象数组与 Underscore 进行比较以找出差异
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Compare 2 arrays of objects with Underscore to find the differnce
提问by Stephen Patten
I have 2 arrays, one is newVal and the other is origVal define
我有 2 个数组，一个是 newVal，另一个是 origVal 定义
orig:
来源：
[
{"ListingId":1762276,"Rating":3,"ListPrice":7411828,"PropertyType":"Residential"},
{"ListingId":1826692,"Rating":3,"ListPrice":650000,"PropertyType":"Residential"},
{"ListingId":1833283,"Rating":4,"ListPrice":950000,"PropertyType":"Residential"},
{"ListingId":1832134,"Rating":3,"ListPrice":850000,"PropertyType":"Residential"},
{"ListingId":1829932,"Rating":4,"ListPrice":750000,"PropertyType":"Residential"},
{"ListingId":1827548,"Rating":5,"ListPrice":650000,"PropertyType":"Residential"}
]
new:
新的：
[
{"ListingId":1762276,"Rating":2,"ListPrice":7411828,"PropertyType":"Residential"},
{"ListingId":1826692,"Rating":3,"ListPrice":650000,"PropertyType":"Residential"},
{"ListingId":1833283,"Rating":4,"ListPrice":950000,"PropertyType":"Residential"},
{"ListingId":1832134,"Rating":3,"ListPrice":850000,"PropertyType":"Residential"},
{"ListingId":1829932,"Rating":4,"ListPrice":750000,"PropertyType":"Residential"},
{"ListingId":1827548,"Rating":5,"ListPrice":650000,"PropertyType":"Residential"}
]
If I change one of the ratings in new, how might I detect that change, and retrieve the changed object?
如果我在 new 中更改其中一个评级，我如何检测该更改并检索更改的对象？
There will only be one change at a time, although I don't think that matters.
一次只会有一个变化，虽然我认为这并不重要。
FYI: These arrays are being produced from an Anjularjs watchcollection
仅供参考：这些数组是从 Anjularjs watchcollection 生成的
$scope.$watchCollection('items', function (new, old) {
}, true);
Thank you, Stephen
谢谢你，斯蒂芬
回答by Jonathan Naguin
Take a look to this:
看看这个：
var a = [
{"ListingId":1762276,"Rating":3,"ListPrice":7411828,"PropertyType":"Residential"},
{"ListingId":1826692,"Rating":3,"ListPrice":650000,"PropertyType":"Residential"},
{"ListingId":1833283,"Rating":4,"ListPrice":950000,"PropertyType":"Residential"},
{"ListingId":1832134,"Rating":3,"ListPrice":850000,"PropertyType":"Residential"},
{"ListingId":1829932,"Rating":4,"ListPrice":750000,"PropertyType":"Residential"},
{"ListingId":1827548,"Rating":5,"ListPrice":650000,"PropertyType":"Residential"}
];
var b = [
{"ListingId":1762276,"Rating":2,"ListPrice":7411828,"PropertyType":"Residential"},
{"ListingId":1826692,"Rating":3,"ListPrice":650000,"PropertyType":"Residential"},
{"ListingId":1833283,"Rating":4,"ListPrice":950000,"PropertyType":"Residential"},
{"ListingId":1832134,"Rating":3,"ListPrice":850000,"PropertyType":"Residential"},
{"ListingId":1829932,"Rating":4,"ListPrice":750000,"PropertyType":"Residential"},
{"ListingId":1827548,"Rating":5,"ListPrice":650000,"PropertyType":"Residential"}
]
var difference = function(array){
var rest = Array.prototype.concat.apply(Array.prototype, Array.prototype.slice.call(arguments, 1));
var containsEquals = function(obj, target) {
if (obj == null) return false;
return _.any(obj, function(value) {
return _.isEqual(value, target);
});
};
return _.filter(array, function(value){ return ! containsEquals(rest, value); });
};
console.log(JSON.stringify(difference(b, a)));
> [{"ListingId":1762276,"Rating":2,"ListPrice":7411828,"PropertyType":"Residential"}]
The code is based on the original function differencefrom underscore, but it performs a deep comparison between objects using isEqual.
回答by Bergi
If the order does not change, a simple iteration will do it. Underscore provides the findmethodfor this task:
如果顺序不变，一个简单的迭代就可以了。Underscore为这个任务提供了find方法：
var changedObj = _.find(newVal, function(obj, index) {
return obj.Rating != oldVal[index].Rating;
});
回答by thecommoner
How about:
怎么样：
const current = [{name:'a'},{name:'b'},{name:'c'}]
const update = [{name:'x'},{name:'a'},{name:'b'},{name:'f'}]
const records = current.concat(update);
const diff = {};
diff.in = []
diff.out = [];
records.forEach(item => {
if(!current.find(cur => item.name == cur.name))diff.in.push(item)
if(!update.find(up => item.name == up.name ))diff.out.push(item)
})
