确定阵列中的位置[重复]

Question

我试图确定数组中的位置。我真的不确定如何处理这种情况

const expect = require('chai').expect;
const answers = require('../src/arrays');

describe('arrays', function() {
    let a;

    beforeEach(function() {
        a = [ 1, 2, 3, 4 ];
    });

    it('expect determine location of a in array', function(expect) {
        expect(answers.indexOf(a, 3)).to.eql(2);
        expect(answers.indexOf(a, 5)).to.eql(-1);

    });

Answer 1

试试这个！

var array = [ 1, 2, 3, 4 ]; 
   
function finding_index(element) { 
  return element === 2; 
} 
  
console.log(array.findIndex(finding_index));