binary-insert.js

/* 
    target: the object to search for in the array
    comparator: (optional) a method for comparing the target object type
    return value: index of a matching item in the array if one exists, otherwise the bitwise complement of the index where the item belongs
*/
Array.prototype.binarySearch = function (target, comparator) {
    var l = 0,
        h = this.length - 1,
        m, comparison;
    comparator = comparator || function (a, b) {
        return (a < b ? -1 : (a > b ? 1 : 0)); /* default comparison method if one was not provided */
    };
    while (l <= h) {
        m = (l + h) >>> 1; /* equivalent to Math.floor((l + h) / 2) but faster */
        comparison = comparator(this[m], target);
        if (comparison < 0) {
            l = m + 1;
        } else if (comparison > 0) {
            h = m - 1;
        } else {
            return m;
        }
    }
    return~l;
};

/*
    target: the object to insert into the array
    duplicate: (optional) whether to insert the object into the array even if a matching object already exists in the array (false by default)
    comparator: (optional) a method for comparing the target object type
    return value: the index where the object was inserted into the array, or the index of a matching object in the array if a match was found and the duplicate parameter was false 
*/
Array.prototype.binaryInsert = function (target, duplicate, comparator) {
    var i = this.binarySearch(target, comparator);
    if (i >= 0) { /* if the binarySearch return value was zero or positive, a matching object was found */
        if (!duplicate) {
            return i;
        }
    } else { /* if the return value was negative, the bitwise complement of the return value is the correct index for this object */
        i = ~i;
    }
    this.splice(i, 0, target);
    return i;
};

const arr = [];
arr.binaryInsert("Zebra");
arr.binaryInsert("Aardvark");
arr.binaryInsert("Mongoose");

console.log(arr);