合并对象数组中的重复对象 [英] Merge duplicate objects in array of objects
问题描述
我有以下对象数组,
var data = [
{
label: "Book1",
data: "US edition"
},
{
label: "Book1",
data: "UK edition"
},
{
label: "Book2",
data: "CAN edition"
}
];
我想根据属性标签"合并重复的对象以便最终输出如下所示,
I want to merge the duplicate objects based on attribute 'label' so that Final output will look like below,
var data = [
{
label: "Book1",
data: ["US edition", "UK edition"] //data attribute is merged
},
{
label: "Book2",
data: "CAN edition"
}
];
有人可以帮我确定方法吗?
Can someone help me identify the approach?
推荐答案
我可能会使用 filter
循环遍历,跟踪我以前见过的对象地图,沿着这些路线(编辑以反映您同意是的,使 (entry).data
始终是一个数组是有意义的):
I would probably loop through with filter
, keeping track of a map of objects I'd seen before, along these lines (edited to reflect your agreeing that yes, it makes sense to make (entry).data
always an array):
var seen = {};
data = data.filter(function(entry) {
var previous;
// Have we seen this label before?
if (seen.hasOwnProperty(entry.label)) {
// Yes, grab it and add this data to it
previous = seen[entry.label];
previous.data.push(entry.data);
// Don't keep this entry, we've merged it into the previous one
return false;
}
// entry.data probably isn't an array; make it one for consistency
if (!Array.isArray(entry.data)) {
entry.data = [entry.data];
}
// Remember that we've seen it
seen[entry.label] = entry;
// Keep this one, we'll merge any others that match into it
return true;
});
在 ES6 环境中,我会使用 seen = new Map()
而不是 seen = {}
.
In an ES6 environment, I'd use seen = new Map()
rather than seen = {}
.
注意:Array.isArray
是由 ES5 定义的,所以一些比较老的浏览器比如 IE8 没有它.不过,它可以很容易地填充/填充:
Note: Array.isArray
was defined by ES5, so some quite older browsers like IE8 won't have it. It can easily be shimmed/polyfilled, though:
if (!Array.isArray) {
Array.isArray = (function() {
var toString = Object.prototype.toString;
return function(a) {
return toString.call(a) === "[object Array]";
};
})();
}
旁注:我可能也总是将 (我们现在已经在上面做了.)entry.data
设为一个数组,即使我没有看到它的两个值,因为一致数据结构更容易处理.我没有在上面这样做,因为你的最终结果显示 data
只是一个字符串,而只有一个匹配条目.
Side note: I'd probably also always make (We've done that above now.)entry.data
an array, even if I didn't see two values for it, because consistent data structures are easier to deal with. I didn't do that above because your end result showed data
being just a string when there was only one matching entry.
实例(ES5 版本):
var data = [
{
label: "Book1",
data: "US edition"
},
{
label: "Book1",
data: "UK edition"
},
{
label: "Book2",
data: "CAN edition"
}
];
snippet.log("Before:");
snippet.log(JSON.stringify(data, null, 2), "pre");
var seen = {};
data = data.filter(function(entry) {
var previous;
// Have we seen this label before?
if (seen.hasOwnProperty(entry.label)) {
// Yes, grab it and add this data to it
previous = seen[entry.label];
previous.data.push(entry.data);
// Don't keep this entry, we've merged it into the previous one
return false;
}
// entry.data probably isn't an array; make it one for consistency
if (!Array.isArray(entry.data)) {
entry.data = [entry.data];
}
// Remember that we've seen it
seen[entry.label] = entry;
// Keep this one, we'll merge any others that match into it
return true;
});
snippet.log("After:");
snippet.log(JSON.stringify(data, null, 2), "pre");
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<script src="http://tjcrowder.github.io/simple-snippets-console/snippet.js"></script>
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