<!DOCTYPE>
<html>
<body>
<img id="traffic" src="assets/red.gif">
<button type="button" onclick="ChangeLights()">Change Lights</button>
<script>
var lights = [
"assets/red.gif",
"assets/yellow.gif",
"assets/green.gif",
"assets/yellow.gif",
];
var index = 0;
function ChangeLights() {
setInterval(function () {ChangeLights();}, 1000);
index = index + 1;
if (index == lights.length) index = 0;
var image = document.getElementById('traffic');
image.src=lights[index];
}
</script>
</body>
</html>
嗨，我正在尝试使用JavaScript创建一个动画脚本，以便在按下按钮时，交通灯序列从红色 - 黄色 - 绿色 - 黄色变为计时器。我只希望序列循环一次。但是，当我在函数中实现setInterval函数时，灯光只会从红色 - 黄色 - 绿色 - 红色变为红色。 谢谢你的帮助！
答案 0 :(得分：1)
var lights = {
red: "https://upload.wikimedia.org/wikipedia/commons/thumb/4/45/Traffic_lights_red.svg/200px-Traffic_lights_red.svg.png",
yellow: "https://upload.wikimedia.org/wikipedia/commons/thumb/1/19/Traffic_lights_yellow.svg/200px-Traffic_lights_yellow.svg.png",
green: "https://upload.wikimedia.org/wikipedia/commons/thumb/b/b2/Traffic_lights_dark_green.svg/200px-Traffic_lights_dark_green.svg.png"
};
var sequence = ['red', 'yellow', 'green', 'yellow'];
function startChangeLights() {
for (var index = 0; index < sequence.length; index++) {
changeLight(index, sequence[index]);
}
function changeLight(index, color) {
setTimeout(function() {
var image = document.getElementById('traffic');
image.src = lights[color];
}, index * 1000);
}
}<div>
<img height=100px id="traffic" src="https://upload.wikimedia.org/wikipedia/commons/thumb/4/45/Traffic_lights_red.svg/200px-Traffic_lights_red.svg.png">
</div>
<div>
<button type="button" onclick="startChangeLights()">Change Lights</button>
</div>
答案 1 :(得分：0)
如果您正在寻找一个时间序列，您必须在javascript中使用“setTimeout”方法，此外，定义如下内部函数：
var lights = [
"assets/red.gif",
"assets/yellow.gif",
"assets/green.gif",
"assets/yellow.gif",
];
var index = 0;
function ChangeLights() {
function innerChangeLight(){
index = index + 1;
if (index == lights.length) index = 0;
var image = document.getElementById('traffic');
image.src=lights[index];
}
innerChangeLight();
setTimeout(function () {
innerChangeLight();
}, 1000);
}<!DOCTYPE>
<html>
<body>
<img id="traffic" src="assets/red.gif">
<button type="button" onclick="ChangeLights()">Change Lights</button>
</body>
</html>
答案 2 :(得分：0)
试试这个：
var lights = [
"assets/red.gif",
"assets/yellow.gif",
"assets/green.gif",
"assets/yellow.gif",
];
var index = 0;
function ChangeLights(){
setInterval(function() {
if(index == lights.length) {
return;
}
var image = document.getElementById('traffic');
image.src=lights[index];
index = index + 1;
}, 1000);
}<img id="traffic" src="assets/red.gif"><br>
<button onclick="ChangeLights()">Change Lights</button>
答案 3 :(得分：0)
交通信号灯在每个灯光下的持续时间不能相同....
所以，我开始扩展这个HTML代码.. 改进的代码在每个灯光中都有不同的秒数：
// Traffic Light
// Improved with different durations in every light!
// But in this html code, i will use input tag instead
var TrafficLights = (function() {
// The image
var imageTag = document.getElementById("lightImg");
// Keep track of whether the sequence is running
var running = false;
// Different stages of the traffic light (Also defines the light)
var stages = [
{
"name": "red",
"path": "https://upload.wikimedia.org/wikipedia/commons/thumb/4/45/Traffic_lights_red.svg/200px-Traffic_lights_red.svg.png",
},
{
"name": "green",
"path": "https://upload.wikimedia.org/wikipedia/commons/thumb/b/b2/Traffic_lights_dark_green.svg/200px-Traffic_lights_dark_green.svg.png"
},
{
"name": "yellow",
"path": "https://upload.wikimedia.org/wikipedia/commons/thumb/1/19/Traffic_lights_yellow.svg/200px-Traffic_lights_yellow.svg.png"
}
];
// Different amount of seconds in every light change (Must be an positive integer!)
var seconds_every_step = [
18,
24,
3
];
// Current stage of the traffic light
var stage = 0;
// Current steps of the traffic light
var steps = 0;
// Timer for automatically changing light
var timer = null;
/** * Start the traffic light sequence * */
function start() {
// Mark that the light sequence is running
running = true;
// Tell the light to change
changeLight();
}
/** * Stop the sequence from running * */
function stop() {
// Mark that the sequence is not running
running = false;
// Stop the automatic timer from running
clearInterval(timer);
}
/** * Change the light to the next one in the sequence * */
function changeLight() {
// If the timer is not running, this function does not need to do anything
if (running === false) {
clearInterval(timer);
return;
} else {};
// If the current stage gets higher than the number of stages there are, reset to 0
if (stage >= stages.length) {
stage = 0;
} else {};
// If the current steps gets higher than the number of seconds in a step there are, reset to 0
if (steps >= seconds_every_step.length) {
steps = 0;
} else {};
// Get the image from the list of stages
var image = stages[stage];
var wait_seconds = seconds_every_step[steps];
// Update the image tag and defines the light name
imageTag.src = image.path;
imageTag.alt = String("Traffic light color is " + image.name + ".");
// Increase the current stage by 1
stage++;
// Increase the current steps by 1
steps++;
// Set a timeout to change the light at the next interval
timer = setTimeout(changeLight, wait_seconds * 1000);
}
// These functions will be available on the `TrafficLights` object to allow interaction
return {
start: start,
stop: stop
}
})();<input type="image" width="20px" id="lightImg" src="" alt="">
<br/>
<p>
<button type="button" onclick="TrafficLights.start()">Start Sequence</button> <button type="button" onclick="TrafficLights.stop()">Stop Sequence</button>
</p>
答案 4 :(得分：-2)
var red = document.getElementById("red");
var yellow = document.getElementById("yellow");
var green = document.getElementById("green");
var btn = document.createElement("BUTTON");
btn.innerHTML = "CLICK ME";
document.body.appendChild(btn);
red.style.opacity = "1";
yellow.style.opacity = "0.2";
green.style.opacity = "0.2";
btn.onclick = function () {
setTimeout(function(){red.style.opacity = "0.2";yellow.style.opacity = "1"; setTimeout(function(){yellow.style.opacity = "0.2";green.style.opacity = "1"; setTimeout(function(){green.style.opacity = "0.2";red.style.opacity = "1"}, 1000);}, 1000);
}, 1000);
}html{
background: linear-gradient(#08f, #fff);
padding: 40px;
width: 170px;
height: 100%;
margin: 0 auto;
}
.trafficlight{
background: #222;
background-image: linear-gradient(transparent 2%, #111 2%, transparent 3%, #111 30%);
width: 170px;
height: 400px;
border-radius: 20px;
position: relative;
border: solid 5px #333;
}
#red{
background: red;
background-image: radial-gradient(brown, transparent);
background-size: 5px 5px;
width: 100px;
height: 100px;
border-radius: 50%;
position: absolute;
top: 20px;
left: 35px;
animation: 13s red infinite;
border: dotted 2px red;
box-shadow:
0 0 20px #111 inset,
0 0 10px red;
}
#yellow{
background: yellow;
background-image: radial-gradient(orange, transparent);
background-size: 5px 5px;
width: 100px;
height: 100px;
border-radius: 50%;
border: dotted 2px yellow;
position: absolute;
top: 145px;
left: 35px;
animation: 13s yellow infinite;
box-shadow:
0 0 20px #111 inset,
0 0 10px yellow;
}
#green{
background: green;
background-image: radial-gradient(lime, transparent);
background-size: 5px 5px;
width: 100px;
height: 100px;
border-radius: 50%;
border: dotted 2px lime;
position: absolute;
top: 270px;
left: 35px;
box-shadow:
0 0 20px #111 inset,
0 0 10px lime;
animation: 13s green infinite;
}<div class="trafficlight">
<div id="red"></div>
<div id="yellow"></div>
<div id="green"></div>
</div>我根据在线示例制作了一个简单的 HTML 和 CSS 交通灯。然后我只是为它创建循环红-黄-绿-红的条件。