Binary Search in Javascript

binary_search.js

const binary_search = (arr, q) => {

    const halfway = (l, h) => { return Math.floor((l + h) / 2) }

    const strcmp = ( str1, str2 ) => {
        // http://kevin.vanzonneveld.net
        // +   original by: Waldo Malqui Silva
        // +      input by: Steve Hilder
        // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
        // +    revised by: gorthaur
        
        return ( ( str1 == str2 ) ? 0 : ( ( str1 > str2 ) ? 1 : -1 ) );
    }
    
    let low = 0, high = arr.length, index = halfway(low, high)
    while(low !== high || strcmp(q, arr[index]) === 0) {
        if (strcmp(q, arr[index]) === 0) {
            return index
        }
        else if (strcmp(q, arr[index]) === 1) {
            low = index + 1
            index = halfway(low, high)
            continue
        }
        else {
            high = index - 1
            index = halfway(low, high)
            continue
        }
    }
    return null
}