javascript put string backward code example

Example 1: javascript string reverse

"this is a test string".split("").reverse().join("");
//"gnirts tset a si siht"

// Or
const reverse = str => [...str].reverse().join('');

// Or
const reverse = str => str.split('').reduce((rev, char)=> `${char}${rev}`, '');

// Or
const reverse = str => (str === '') ? '' : `${reverse(str.substr(1))}${str.charAt(0)}`;

// Example
reverse('hello world');     // 'dlrow olleh'

Example 2: javascript reverse string

function reverseString(str) {
    // Step 1. Create an empty string that will host the new created string
    var newString = "";
 
    // Step 2. Create the FOR loop
    /* The starting point of the loop will be (str.length - 1) which corresponds to the 
       last character of the string, "o"
       As long as i is greater than or equals 0, the loop will go on
       We decrement i after each iteration */
    for (var i = str.length - 1; i >= 0; i--) { 
        newString += str[i]; // or newString = newString + str[i];
    }
    /* Here hello's length equals 5
        For each iteration: i = str.length - 1 and newString = newString + str[i]
        First iteration:    i = 5 - 1 = 4,         newString = "" + "o" = "o"
        Second iteration:   i = 4 - 1 = 3,         newString = "o" + "l" = "ol"
        Third iteration:    i = 3 - 1 = 2,         newString = "ol" + "l" = "oll"
        Fourth iteration:   i = 2 - 1 = 1,         newString = "oll" + "e" = "olle"
        Fifth iteration:    i = 1 - 1 = 0,         newString = "olle" + "h" = "olleh"
    End of the FOR Loop*/
 
    // Step 3. Return the reversed string
    return newString; // "olleh"
}
 
reverseString('hello');