firstReverse.js

/**
 * First Reverse
 * Have the function FirstReverse(str) take the str parameter
 * being passed and return the string in reversed order.
 * For example: if the input string is "Hello World and Coders"
 * then your program should return the string sredoC dna dlroW olleH.
 *
 * Test Cases
 * > firstReverse "Hello World and Coders"
 * "sredoC dna dlroW olleH"
 *
 * > firstReverse "coderbyte"
 * "etybredoc"
 */
 
function firstReverse(str) {
  return str
    .split("")
    .reverse()
    .join("");
}

Other solution could be

function firstReverse(str) {
  let mstr = "";
  for (let i = 1; i <= str.length; i++) {
    mstr += str[str.length - i];
  }
  return mstr;
}

Another one is

function firstReverse(str) {
	if (typeof str != String) {str += ''}
	var str1 = [], str2 = [], i = 0;
	while (i < str.length) {
	  str1.push(str.substr(i++,1) );

	}
	for (i in str1) { 
	  str2.unshift(str1[i]); 
	}
	return String(str2.join('') ); 
}