将 2 个元素数组的 JavaScript 数组转换为对象键值对
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Convert JavaScript array of 2 element arrays into object key value pairs
提问by Fred Guest
What is the fastest algorithm for getting from something like this:
从这样的东西中获得最快的算法是什么：
var array = [ [1,'a'], [2,'b'], [3,'c'] ];
to something like this:
到这样的事情：
Object { 1: "a", 2: "b", 3: "c" }
so far this is what i've come up with:
到目前为止，这是我想出的：
function objectify(array) {
var object = {};
array.forEach(function(element) {
object[element[0]] = element[1];
});
return object;
}
which works fine, but it seems kind of clumsy. Is there a better way? Would something like reduce()work and would that be any faster?
这工作正常，但似乎有点笨拙。有没有更好的办法？像reduce()这样的东西会起作用吗，那会更快吗？
回答by Alnitak
You could indeed use Array.prototype.reduce:
你确实可以使用Array.prototype.reduce：
function objectify(array) {
return array.reduce(function(p, c) {
p[c[0]] = c[1];
return p;
}, {});
}
where pis the result of the previous iteration, initially {}, and cis the current element of the array.
其中p是前一次迭代的结果，最初{}，并且c是阵列的当前元素。
It's unlikely to be any faster than array.forEach, but it is IMHO cleaner. I don't believe there's any simpler implementation than this.
它不太可能比 快array.forEach，但恕我直言，它更干净。我认为没有比这更简单的实现了。
NB: a function to do exactly this already exists in the Underscorelibrary: _.object(array)
注意：Underscore库中已经存在执行此操作的函数：_.object(array)
回答by Phrogz
Terse version using modern syntax:
使用现代语法的简洁版本：
let objectify = a => a.reduce( (o,[k,v]) => (o[k]=v,o), {} );
I use this technique as part of a terse query string parser:
我将此技术用作简洁查询字符串解析器的一部分：
// Converts "?foo=bar&j=1&go" into { foo:'bar', j:'1', go:true }
function parseQueryString(qs) {
var q = decodeURIComponent;
return qs.replace(/^\?/,'').split('&').map(s => s.split('='))
.reduce((o,[k,v]) => (o[q(k)] = v?q(v):true, o), {});
}
回答by Penny Liu
With Object.fromEntries, you can convert from Arrayto Object:
使用Object.fromEntries，您可以从 转换Array为Object：
var array = [
[1, 'a'],
[2, 'b'],
[3, 'c']
];
var object = Object.fromEntries(array);
console.log(object);回答by Uri Klar
Lodash has a _.fromPairsmethod that does exactly that.
Lodash 有一个_.fromPairs方法可以做到这一点。
From the documentation:_.fromPairs([['a', 1], ['b', 2]]);
// => { 'a': 1, 'b': 2 }
从文档：_.fromPairs([['a', 1], ['b', 2]]);
// => { 'a': 1, 'b': 2 }
回答by thefourtheye
You can wrap the entire thing within Array.prototype.reduce, like this
你可以把整个东西都包裹在里面Array.prototype.reduce，像这样
function objectify(array) {
return array.reduce(function(result, currentArray) {
result[currentArray[0]] = currentArray[1];
return result;
}, {});
}
console.log(objectify([ [1, 'a'], [2, 'b'], [3, 'c'] ]));
# { '1': 'a', '2': 'b', '3': 'c' }
We are just accumulating the key-value pairs in the resultobject and finally the result of reducewill be the resultobject and we are returning it as the actual result.
我们只是在result对象中累积键值对，最后将结果reduce作为result对象，我们将其作为实际结果返回。
