How to declare this variable

Question

I am working on a app using App Lab (code.org). I am sorry if this is a very easy fix. I started javascript just 3 months ago and this is my first project.

I want the countdown to start once they click button "start_city_game_button" however I am getting this error

setInterval() callback parameter value (1000) is not a function

and

setInterval() milisecond parameter value (undefined) is not a number.

These errors appear in line 2.

var city_time = 60;
var city_time_counter = setInterval(1000);

function cityTimer() {
city_time = city_time -1;
  clearInterval(city_time_counter);
  }
}

I expect the timer to start once level has been started, however the time actually starts when the app starts. I have gone through many drafts of this code to find the correct anwser but I cannot find the way.

onEvent("back_mainscreen", "click", function() {
  setScreen("start_screen");
});
onEvent("instructions", "click", function() {
  setScreen("instructions");
});
onEvent("startgame", "click", function() {
  setScreen("city_screen");
});

// City Code
var city_tries = 0;
var city_time = 60;
var city_time_counter = setInterval(1000);



onEvent("start_game_city_button", "click",function() {
city_time = city_time -1;
console.log(city_time);
setText("second_city_time", city_time);
  if (city_time === 0) {
  setScreen("city_screen");
  clearInterval(city_time_counter);
  }
});
  
  onEvent("start_game_city_button", "click", function() {
  console.log("CONSOLE: Player Started City Level");
  console.log(city_tries);
  setScreen("city_game_screen");
  city_tries = city_tries + 1;
});




var score = 0;
onEvent("deer", "click", function() {
  setPosition("deer", randomNumber(50,240), randomNumber(50, 400));
  score = score + 1;
 setText("score_label", score);
});
// Ocean Code
var ocean_tries = 0;
onEvent("ocean_start_button", "click", function() {
    ocean_tries = ocean_tries + 1;
  console.log("CONSOLE: Player Started Ocean Level. Try");
    console.log(ocean_tries);
});

Answer 1

The first parameter to setInterval is a function. And second parameter is amount of time.

var city_time_counter = setInterval(cityTimer,1000);

If you want the timer to start on click then attach a listener to the element and setInterval in that.

document.getElementById("start_city_game_button").addEventListener('click',()=>{
    city_time_counter = setInterval(1000);
})

And also if you need to decrease variable by 1 you can use a shorthand for that.

city_time = city_time -1;

The above line is same as

city_time--;