JS native AppendChild's Bug solving experience sharing _javascript tips

AppendChild is mainly used to append nodes to the last

Copy Code code as follows:

Window.onload = function () {
var ul2 = document.getElementById (' ul2 ');
var oli = document.getelementsbytagname (' li ');
for (Var i=0;i<oli.length;i++) {
Ul2.appendchild (Oli[i]);
}
}
<ul id= "UL1" >
<li>1</li>
<li>2</li>
<li>3</li>
<li>4</li>
<li>5</li>
<li>6</li>
</ul>
<ul id= "Ul2" >
</ul>

Insert the UL1 content into the UL2, which is actually moving instead of copying this to remember
You can look at the effect
Why this effect is due to the cycle of time because of the continuous moving cause length changes if you use for the start length has been fixed so that there is a problem, so to change

Copy Code code as follows:

while (Oli.length) {
Ul2.appendchild (Oli[0]);
}

It's all about inserting the first one so you can try.