比如这个函数输入一个1，那么要求函数返回A？

Question

// 比如这个函数输入一个1，那么要求函数返回A
const A = [1,2,3];
const B = [4,5,6];
const C = [7,8,9];

function test(num) {

}

Answer 1

  // 比如这个函数输入一个1，那么要求函数返回A
  const A = [1, 2, 3];
  const B = [4, 5, 6];
  const C = [7, 8, 9];

  function test (num) {
    let obj = { A, B, C }
    for (let key in obj) {
      if (obj[key].includes(num)) {
        return key
      }
    }
  }

  console.log(test(1));

Answer 2

const test = num => [A,B,C].find(arr => arr.includes(num))

Answer 3

function test(num) {
    [A, B, C].forEach((arr) => {
        if (arr.indexOf(num) > -1) {
            console.log(arr);
        }
    });
}