javaScript for循环几种使用方法

for/in 循环：

<!DOCTYPE html>
<html>
<body>
<h3>for/in循环</h3>

<button onclick="firstFunction()">For/in：循环遍历对象的（"dog"）属性</button>
<p id = "tex1"></p>
<script>

function firstFunction(){
var a;
var variable = "";
var dog = {fname:"雪白",age:5,phone:17709320827,adress:"西安市雁塔区510所"};
for(a in dog){
    variable = variable + dog[a] + "<br>";
}
document.getElementById("tex1").innerHTML = variable;
}
</script>
</body>
</html>

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