通过数组中每个 JSON 对象中的值从 JSON 数组中删除重复项

Question

如果数组中有两个 JSON 对象对于特定字段具有相同的值，那么我想将它们标记为重复。我想删除其中之一。同样，当有多个重复时，我只想保留最后一个对象（最新）。如果这是输入：

names_array = [
    {name: "a",  age: 15},
    {name: "a",  age: 16},
    {name: "a",  age: 17},
    {name: "b",  age: 18}
    {name: "b",  age: 19}];

我希望输出是

names_array_new = 
    {name: "a",  age: 17},
    {name: "b",  age: 19}];

我已经搜索过这个，但只找到了如何在整个对象相同时删除重复项。

Answer 1

应该这样做：

names_array = [
    {name: "a",  age: 15},
    {name: "a",  age: 16},
    {name: "a",  age: 17},
    {name: "b",  age: 18},
    {name: "b",  age: 19}];

function hash(o){
    return o.name;
}    

var hashesFound = {};

names_array.forEach(function(o){
    hashesFound[hash(o)] = o;
})

var results = Object.keys(hashesFound).map(function(k){
    return hashesFound[k];
})

hash 函数决定哪些对象是重复的，hashesFound 对象将每个哈希值与产生该哈希的最新对象一起存储，results 数组包含匹配的对象。

Answer 2

稍微不同的方法：

var names_array = [
    { name: "a", age: 15 },
    { name: "a", age: 16 },
    { name: "a", age: 17 },
    { name: "b", age: 18 },
    { name: "b", age: 19 }
];

var names_array_new = names_array.reduceRight(function (r, a) {
    r.some(function (b) { return a.name === b.name; }) || r.push(a);
    return r;
}, []);

document.getElementById('out').innerHTML = JSON.stringify(names_array_new, 0, 4);

<pre id="out"></pre>

Answer 3

var names_array = [
{name: "a", age: 15},
{name: "a", age: 16},
{name: "a", age: 17},
{name: "b", age: 18},
{name: "b", age: 19}];

function removeDuplicate(arr, prop) {
var new_arr = [];
var lookup = {};
for (var i in arr) {
    lookup[arr[i][prop]] = arr[i];
}
for (i in lookup) {
    new_arr.push(lookup[i]);
}
return new_arr;}
var newArray = removeDuplicate(names_array, 'name');
console.log("Result "+newArray);

Answer 4

Array.from(new Set(brand.map(obj => JSON.stringify(obj)))).map(item => JSON.parse(item))