jQuery更改类的所有边界

Question

Why is not $( "demo" ).css("border", "1px solid #FFF"); working? Every other part of the function is working, but not that one. The class "demo" is a regular from "page1.html".

<script>
var button = 0;
var activecolor = 0;
function pressbutton(a){
button = a;
var color1 = "#46B29D";
var color2 = "#F0CA4D";
var color3 = "#E37B40";
if (button === 1) {
activecolor = color1;
document.getElementById("button1").className = "activemenubutton";
document.getElementById("button2").className = "menubutton";
document.getElementById("button3").className = "menubutton";
} else if (button === 2){
activecolor = color2;
document.getElementById("button1").className = "menubutton";
document.getElementById("button2").className = "activemenubutton";
document.getElementById("button3").className = "menubutton";
} else if (button === 3){
activecolor = color3;
document.getElementById("button1").className = "menubutton";
document.getElementById("button2").className = "menubutton";
document.getElementById("button3").className = "activemenubutton";
}

document.getElementById("textholder").style.borderTop = "1px solid " + activecolor;
document.getElementById("textholder").style.borderBottom = "1px solid " + activecolor;
document.getElementById("textholder").style.color= activecolor;


$("#textholder").load("Page" + a + ".html");
$( "demo" ).css("border", "1px solid #FFF");

} //end of function

</script>

Answer 1

You're missing a full stop. $( ".demo" ).css("border", "1px solid #FFF");

Answer 2

$("demo")

hits all < demo > tags, in case they exists, which I'm sure don't. You're missing

$(".demo") or $("#demo") 

to hit elements with class or id 'demo'.

On top of that, load() is an asynchronous function, so the css() call will usually fire before the page is loaded, therefore not modifying your element styles. You shold replace the load() and css() calls this way:

$("#placeholder").load("Page" + a + ".html" , function(){
   $(".demo").css('border' , '1px solid #FFF');

})

So you force the css assignement to wait until the content is loaded from the server.