Repeated String Match

Description

Given two strings A and B, find the minimum number of times A has to be repeated such that B is a substring of it. If no such solution, return -1.

For example, with A = "abcd" and B = "cdabcdab".

Return 3, because by repeating A three times (“abcdabcdabcd”), B is a substring of it; and B is not a substring of A repeated two times ("abcdabcd").

Note:
The length of A and B will be between 1 and 10000.

Solution(javascript)

/**
 * @param {string} A
 * @param {string} B
 * @return {number}
 */
var repeatedStringMatch = function(A, B) {
    let num = 1, s = A;
    while(s.length < B.length){
            s += A;
            num++;
    }
    
    if(s.includes(B)) return num;
    if((s+A).includes(B)) return num+1;
    return -1;
};