2

I'm not clear on the correct syntax to do the following.

  • I have tried eval() I have tried [] and {[]} as well..

I start with this:

var player1InitStart = 0;
var player2InitStart = 0;
var player3InitStart = 0;
var player4InitStart = 0;

var playerID =  event.target.id; // will return, player1, 2, 3, 4

To be used in a check like so:

if(eval(playerID + "InitString") == 0){
    //do something, first time starting video
    eval(playerID + "InitString") = 1;
    alert('First Time Playing Video' + eval(playerID + "InitString"));
}

I am trying to use the playerID value together with the string: "InitStart"..

so I can then update the target xxInitStart variable above.

How can I concatenate the var playerID with the string InitStart so I can now target one of the playerXInitSTart variables to update it?

Update: answer/solution that worked for me-

  • no clue why the $ character is being used? (reminds me of PHP)

  • no clue why the back tick marks '' are there either? ''

    var playerID = event.target.getIframe().id; var targetInitID = ${playerID}InitStart;

    //access (get or set) alert(window[targetInitID]); window[targetInitID] = 1;

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2
  • 3
    Don't. Use an object (or array) instead of 4 separate variables Commented Feb 8, 2019 at 23:36
  • Can you put that into some context? What exactly would I be putting into an array? I still need to take the returned value/variable (playerID, which will be player1, player2, player 3 or player4).. and tack on the InitStart string/extension to target a variable.. I'm failing to see how an array comes into play here? or helps? Commented Feb 8, 2019 at 23:41

1 Answer 1

Reset to default
1

Here we build string and address window[yourvar] to increment, does this work for you

var player1InitStart = 0;
var player2InitStart = 0;
var player3InitStart = 0;
var player4InitStart = 0;

//var playerID =  event.target.id; // will return, player1, 2, 3, 4

document.querySelectorAll('div').forEach(div => {
  div.addEventListener('click', clickEvent);
});

function clickEvent(event) {
  let playerID = `${event.target.id}InitStart`;
  window[playerID] += 1;
  logVars();
}

function logVars() {
  console.log(player1InitStart);
  console.log(player2InitStart);
  console.log(player3InitStart);
  console.log(player4InitStart);
}
<div id="player1">1</div>
<div id="player2">2</div>
<div id="player3">3</div>
<div id="player4">4</div>

Here is a solution that follows CertainPerformance advice:

var players = {
  player1InitStart: 0,
  player2InitStart: 0,
  player3InitStart: 0,
  player4InitStart: 0
};

document.querySelectorAll('div').forEach(div => {
  div.addEventListener('click', clickEvent);
});

function clickEvent(event) {
  let playerID = `${event.target.id}InitStart`;
  players[playerID] += 1;
  logVars();
}

function logVars() {
  for(let k in players) {
    console.log(players[k]);
  }
}
<div id="player1">1</div>
<div id="player2">2</div>
<div id="player3">3</div>
<div id="player4">4</div>

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11 Comments

while this should work, sometimes we need to not answer the direct question and instead steer OP towards a better approach. This is one of those times.
Why & where does 'window' come from? Also where does the 'let' do in the code above?
@whispers: if this javascript runs in a browser, the browser exposes global variable window
per @SergioTulentsev I agree the second solution, using an object is better. Even better would be an array of player objects.
I am just trying to set/update a variable to show that is has been played once. Why are there back ticks on the line that is concatenating the two pieces of data? I see no reason to put those variables in an array.. there will never be any looping going on to update them.
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