Works same as Java’s String.hashCode()

JavaScriptStringHashCode.js

/**
 * String hash code
 * @param {String} str
 * @return {int}
 */
function hashCode(str) {
  for (var result = 0, i = 0; i < str.length; i++) {
		result = (result << 5) - result + str.charCodeAt(i);
		result &= result;
	}
	return result;
}
// Compressed
function(e){for(var r=0,i=0;i<e.length;i++)r=(r<<5)-r+e.charCodeAt(i),r&=r;return r};
// Usage
console.log(hashCode("Secret message"));