# JS Array Element to Func True

1. [Basic Algorithm Scripting: Finders Keepers | freeCodeCamp.org](https://www.freecodecamp.org/learn/javascript-algorithms-and-data-structures/basic-algorithm-scripting/finders-keepers)
2. [freeCodeCamp Challenge Guide: Finders Keepers - Guide - The freeCodeCamp Forum](https://forum.freecodecamp.org/t/freecodecamp-challenge-guide-finders-keepers/16016)

原始代码：

\`\`\`js function findElement(arr, func) { let num = 0 return num }

console.log(findElement([1, 2, 3, 4], (num) => num % 2 === 0)) ```

看过参考答案后，发现：原来还可以这样！

## for

\`\`\`js function findElement(arr, func) { let num = 0

for (let i = 0; i < arr.length; i++) { num = arr[i] if (func(num)) { return num } } return undefined }

console.log(findElement([1, 2, 3, 4], (num) => num % 2 === 0)) ```

## find()

\`\`\`js function findElement(arr, func) { return arr.find(func) }

console.log(findElement([1, 2, 3, 4], (num) => num % 2 === 0)) ```

## map()

\`\`\`js function findElement(arr, func) { return arr[arr.map(func).indexOf(true)] }

console.log(findElement([1, 2, 3, 4], (num) => num % 2 === 0)) ```

## 递归

\`\`\`js function findElement(arr, func) { return arr.length && !func(arr[0]) ? findElement(arr.slice(1), func) : arr[0] }

console.log(findElement([1, 2, 3, 4], (num) => num % 2 === 2)) ```


相关：[[js|js]]