feat(ts) migrate StringUtils to TS

modules/util/StringUtils.js → modules/util/StringUtils.ts

  * Implements a simple hash code for a string (see
  * https://en.wikipedia.org/wiki/Java_hashCode()).
  *
- * @param {string} The string to return a hash of.
- * @return {Number} the integer hash code of the string.
+ * @param {string} string - The string to return a hash of.
+ * @return {number} the integer hash code of the string.
  */
-function integerHash(string) {
+function integerHash(string: string): number {
     if (!string) {
         return 0;
     }
 
-    let char, hash = 0, i;
+    let char: number, hash = 0;
 
-    for (i = 0; i < string.length; i++) {
+    for (let i = 0; i < string.length; i++) {
         char = string.charCodeAt(i);
         hash += char * Math.pow(31, string.length - 1 - i);
         hash = Math.abs(hash | 0); // eslint-disable-line no-bitwise
     return hash;
 }
 
-module.exports = { integerHash };
+export default integerHash;