How to find permutations of substr in a string (problem from CtCI)

findSubStrPerm.js

function excise(str, index) { // helper function to remove char from substr
    return str.slice(0, index) + str.slice(index+1);
}

function compare(template, x) { // compares two str of equal length
    if (template.length !== x.length) return false;
    if (template === x) {
        return true;
    } else if (template.length === 1) {
        return false;
    }
    const j = x.indexOf(template[0]);
    if (j !== -1) {
        return compare(template.slice(1), excise(x, j));
    }
}


function findSubStr(s, b) {
    let results = [];
    for (let i = 0; i < b.length; i++) {
        if (s.indexOf(b[i]) !== -1) { // start scan for the next s.length - 1 characters
            let currentThread = b.slice(i, i+s.length);
            if (compare(currentThread, s)) {
                results.push(i);
            } else continue;
        }
    }
    return results;
}

let s = 'abbc', b = 'cbabadcbbabbcb';
findSubStr(s, b) // => [0, 6, 9]