find the before number in a list javascript code example

Example 1: find element in array javascript

const simpleArray = [3, 5, 7, 15];
const objectArray = [{ name: 'John' }, { name: 'Emma' }]

console.log( simpleArray.find(e => e === 7) )
// expected output 7

console.log( simpleArray.find(e => e === 10) )
// expected output undefined

console.log( objectArray.find(e => e.name === 'John') )
// expected output { name: 'John' }

Example 2: javascript find first element of array

let array = ["a", "b", "c", "d", "e"];

// Both first1 and first2 have the same value.
let [first1] = array;
let first2 = array[0];