Given a string change every second letter to an uppercase ‘Z’. Assume there are no space. let str1 = “javascript”;

// Given a string change the every second letter to an uppercase ‘Z’. Assume there are no space.
let string be javascript
// Example output:
// jZvZsZrZpZ OR each letter on a new line

// *********** HERE IS MY CODE **********************

> let newarr = str1.split(''); 
> let newword = "Z";
> for(i = 1; i < newarr.lenth; i += 2){
> newarr[i] = newword; newword.join('');}
> 
> console.log(newword);

// *************** Here is my other code I tried ****************

> let newarr = str1.split(''); 
> for(i = 1; i < newarr.lenth; i+=2){
> newarr.replace('newarr[i]' , 'z'); newarr.join('');}
> 
> console.log(newarr);

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Which code closer to correct ? And where Did I go wrong for both codes??