Trying to set a span element equal to a variable value in a JS Rock, Paper, Scissors Game

Beside your typo idea= / id= …
you could drastically minify your game logic and code by using indexes integers.

Game of integers

• Use data-* attribute for user buttons. The attributes should hold numerical values 0, 1, 2. On click, the value will represents the player choice.
• The AI should play numbers too: const AI = ~~(Math.random() * 3) // 0, 1, 2

Now that you know AI and Player both use integers (instead of strange letters combinations), you can store the Move names into an array const moves = ["Rock", "Paper", "Scissors"]; (where 0 is Rock… etc)

Rock Paper Scissors Logic

The game has three possible round resolutions, PL wins, AI wins, Draw.
Let’s convert those “human” values to integers, in the same order:

• 0 = PL win
• 1 = AI win
• 2 = Draw

Here’s how to calculate those:

Draw

To calculate a Draw is the simplest. It’s when both AI and PL integers are equal. Let’s return 2

result = PL === AI ? 2

Player wins

To calculate Player win, simply increment AI choice by 1 and do a modulo 3. If the result of this operation is equal to player’s choice, than Player must have won! Let’s return 0

AI wins

Else, since our game has only 3 possible states, it’s not a draw, and it’s not a player win, than must be AI win! And let’s return 1

const result = PL===AI ? 2 : (AI+1)%3 === PL? 0 : 1; // Possible results: 0, 1, 2

The cool thing in having a game result index based too is that now you can use also an array of messages like messages = ["You won!", "AI won", "it's a draw!", ] and get the desired message by the result index!. And bonus! You can also increment the score array values, 0 being the player’s index and 1 being AIs!

const moves = ["Rock", "Paper", "Scissors"],
  messages  = ["You won!", "AI won", "It's a draw!"], // [PL, AI, draw]
  score     = [0, 0, 0],                              // [PL, AI, draw]
  EL = sel => document.querySelector(sel),
  EL_result  = EL("#result"),
  EL_PLScore = EL("#PLScore"),
  EL_AIScore = EL("#AIScore");

function game() {
  const PL = +this.dataset.playermove;  // Get dataset value as integer
  const AI = ~~(Math.random() * 3);     // All you need: 0, 1, 2
  const result = PL === AI ? 2 : (AI + 1) % 3 === PL ? 0 : 1; // 0=PLwins 1=AIwins 2=draw 

  score[result]++; // Increment PL or AI's score (Increments number of draws too ;) )
  EL_result.innerHTML = `You: ${moves[PL]}<br>AI: ${moves[AI]}<br>${messages[result]}`;
  EL_PLScore.textContent = score[0];
  EL_AIScore.textContent = score[1];
}

// EVENTS:
document.querySelectorAll("[data-playermove]")
  .forEach(el => el.addEventListener("click", game));

<button data-playermove="0">ROCK</button>
<button data-playermove="1">PAPER</button>
<button data-playermove="2">SCISSORS</button>

<br>

YOU | <span id="PLScore">0</span>:<span id="AIScore">0</span> | AI

<div id="result"></div>