Title Case a Sentence- white-space

JavaScript
1

Tell us what’s happening:

i am through with the problem but i want to insert white space in between the output not including the last part something like this I_Am_Happy where “_” is the white space and not I_am_happy

Your code so far


function titleCase(str) {
  let arr = str.split(" ")
  let upper = ""
  let complete =""
  for (var i = 0; i < arr.length; i++) {
     upper = arr[i][0].toUpperCase() + arr[i].slice(1);
    
    complete += " " + {upper};
    
  }
  console.log(complete);
  return complete;
}

titleCase("I'm a little tea pot");

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36.

Link to the challenge:
https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/basic-algorithm-scripting/title-case-a-sentence/

3

i want the code to output I_A_Happy and not I_am_Happy where "" represent white space that is each word of the string must be capitalised with white space between them i have achieved this but their is a white space at end like I_Am_Happy