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错误在于图像没有改变。该代码不会替换下一个状态的交通灯的图像。谁能帮忙? 我遇到了我的程序错误。错误是(我认为)正在改变图像的来源。
<!DOCTYPE html>
<html>
<head>Traffic Lights</head>
<body onload = "setInterval(MainSequence(), 2000)">
<h1>Javascript Traffic Lights</h1>
<button onclick = "MainSequence()">Click here to change the lights</button>
<img id = "myImage" src = "RedLight.png" width = "270" height = "400"></img>
<script>
var LightStates = newArray("RedLight.png", "RedandAmberLight.png", "GreenLight.png", "AmberLight.png");
var image = document.getElementById("myImage");
function MainSequence(){
if (image.src === (LightStates[0])){
//changes the source of the image
image.src = LightStates[1];
return;
}
if (image.src === (LightStates[1])){
image.src = LightStates[2];
return;
}
if (image.src === (LightStates[2])){
image.src === LightStates[3];
return;
}
if (image.src === (LightStates[3])){
image.src = LightStates[0];
return;
}
};
</script>
</body>
</html>