Example of moving a drop-down list select from the left border to the right_javascript skills

When the following statement is called when the page has not been loaded, the "add" object cannot be obtained, and the prompt is empty or not an object

Copy code The code is as follows:

document.getElementById("add").onclick = function(){
alert("hello");
}

Objects that are available when used

Copy code The code is as follows:

window. onload = function(){
document.getElementById("add").onclick = function(){
alert("hello");
}
}

Copy code The code is as follows:

< option value="1">Option 1 Option 2 Option 3 Option 4 Option 5 Option 6

Option 8