Here is my code for a traffic light's sequences. I was wondering how I could add a timer in to change the traffic light colour every 3 seconds, for example, when the button is clicked. Thanks!
<!DOCTYPE html>
<html>
<body>
<h1>JavaScript Task 3</h1>
<p>This is my Traffic Light script</p>
<img id="light" src="./assets/red.jpg">
<button type="button" onclick="changeLights()">Change Lights</button>
<script>
var list = ["./assets/red.jpg","./assets/redamber.jpg", "./assets/green.jpg","./assets/amber.jpg" ];
var index = 0;
function changeLights() {
index = index + 1;
if (index == list.length)
index = 0;
var image = document.getElementById('light');
image.src = list[index];
}
</script>
</body>
</html>
Here is my code for a traffic light's sequences. I was wondering how I could add a timer in to change the traffic light colour every 3 seconds, for example, when the button is clicked. Thanks!
<!DOCTYPE html>
<html>
<body>
<h1>JavaScript Task 3</h1>
<p>This is my Traffic Light script</p>
<img id="light" src="./assets/red.jpg">
<button type="button" onclick="changeLights()">Change Lights</button>
<script>
var list = ["./assets/red.jpg","./assets/redamber.jpg", "./assets/green.jpg","./assets/amber.jpg" ];
var index = 0;
function changeLights() {
index = index + 1;
if (index == list.length)
index = 0;
var image = document.getElementById('light');
image.src = list[index];
}
</script>
</body>
</html>
-
2
setInterval(changeLights,3000)... – Niet the Dark Absol Commented Apr 28, 2016 at 16:23 -
Has your teacher taught you about
setTimeoutorsetInterval? – Mike Cluck Commented Apr 28, 2016 at 16:23 - 1 stackoverflow./questions/36920320/… stackoverflow./questions/34653900/… stackoverflow./questions/37906626/… stackoverflow./questions/35920989/… stackoverflow./questions/31747318/… stackoverflow./questions/37796563/… – le_m Commented Jun 21, 2016 at 9:21
- Can we auto tag "traffic light sequence" questions as duplicates? – evolutionxbox Commented Feb 17, 2017 at 9:58
- Sure, feel free – K. Smith Commented Feb 21, 2017 at 19:13
2 Answers
Reset to default 2Use the setInterval function.
The first parameter is the function you want to call and the second parameter is how often it should be called, in milliseconds.
var timer = setInterval(changeLights,3000);
var list = ["./assets/red.jpg","./assets/redamber.jpg", "./assets/green.jpg","./assets/amber.jpg" ];
var index = 0;
function changeLights() {
index = index + 1;
if (index == list.length)
index = 0;
var image = document.getElementById('light');
image.src=list[index]; }
var timer = setInterval(changeLights,3000);<h1>JavaScript Task 3</h1>
<p>This is my Traffic Light script</p>
<img id="light" src="./assets/red.jpg"> <button type="button"
onclick="changeLights()">Change Lights</button> You can set a static timer with setTimeout(function, time);
In your case, if you want a repeating timer every 3 seconds constantly, you can have setTimeout run every time the changeLights() function ends
See w3schools article on timing
var timer;
function changeLights() {
index = index + 1;
if (index == list.length)
index = 0;
var image = document.getElementById('light');
image.src=list[index];
timer = setTimeout("changeLights", 3000);
}
With that change, once you start the lights, the function will repeat every 3 seconds.
The timer variable also alows you to stop the timer (perhaps in your case with another button) with:
clearTimeout(timer);
Hope this helps