[英]How to get an array of values based on an array of indexes?
我有一組兩個數組。 一個包含一些水果值作為字符串,另一個包含一些隨機數。 在這里,我認為數字數組是水果數組的索引。 給定索引數組中的數字,如何獲得新的水果數組?
樣例代碼:
var resultArr = [];
var fruitier = ["apple", "orange", "grapes", "pineapple", "fig", "banana", "jackfruit", "pomegranate"];
var indexArr = [0, 2, 4];
輸出:
resultArr = ["apple", "grapes", "fig"];
使用.map
:
var resultArr = indexArr.map(i => fruitier[i])
var fruitier = ['apple', 'orange', 'grapes', 'pineapple', 'fig', 'banana', 'jackfruit', 'pomegranate']; var indexArr = [0, 2, 4]; var resultArr = _.at(fruitier, indexArr); console.log(resultArr);
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.16.6/lodash.min.js"></script>
for(var i = 0; i < indexArr.length; i++)
resultArr.push(fruitier[indexArr[i]]);
您可以使用for..of
循環
for (var key of indexArr) resultArr[resultArr.length] = fruitier[key];
Array#map工作原理( 文檔 )
const getFromIndex = (array, indexes) => indexes.map((index) => array[index]);
您也可以使用Array#filter( 文檔 )
const fruitier = ['apple', 'orange', 'grapes', 'pineapple', 'fig', 'banana', 'jackfruit', 'pomegranate'];
const indexArr = [0, 2, 4];
const getFromIndex = (array, indexes) => {
return array.filter((element, index) => indexes.includes(index));
};
或Array#reduce( 文檔 )
const getFromIndex = (array, indexes) => {
return indexes.reduce((result, i) => result.concat(array[i]), []);
};
使用lodash pullAt
var fruitier = ["apple", "orange", "grapes", "pineapple", "fig", "banana",
"jackfruit", "pomegranate"];
var indexArr = [0, 2, 4];
var resultArr = _.pullAt(fruitier, indexArr);
console.log(resultArr);
// ["apple", "grapes", "fig"]
<script src="https://cdn.jsdelivr.net/npm/lodash@4.17.11/lodash.min.js"></script>
除了上面對_.at()的建議外,需要注意的主要區別是-此方法會改變輸入數組。
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