largestNumber.js

/*
CodeSignal: Given an integer n, return the largest number that contains exactly n digits.

Example

For n = 2, the output should be
largestNumber(n) = 99.

Input/Output

[execution time limit] 4 seconds (js)

[input] integer n

Guaranteed constraints:
1 ≤ n ≤ 9.

[output] integer

The largest integer of length n.
*/

// Solution : 

function largestNumber(n) {
    let arr = [];
    for(let i = 0; i < n; i++) {
        // Push a 9 into arr for each digit in n
        arr.push(9)
    }
    
    // arr now contains [9, 9]
    
    // Use join to convert [9, 9] to '99'
    let answer = arr.join('');
    
    // Unary operator turns '99' into 99
    return +answer;
  
}