Question

Arrow_onmouseover is attached with the ‘onmouseover’ event of an object. I get a ‘timeline is not defined’ JS error when the onmouseover event occurs. I know this relates to the variable scope. How can I correct this.

function startloop()
{
    var changer = setInterval("changecontents();", 2000);
    var timeline = setInterval("change();", 2000);  
}

window.onload = startloop();

function arrow_onmouseover()
{ 
window.clearInterval(timeline);
window.clearInterval(changer);
}

Also what is the difference between a function called as Function(); and Function; . I believe this may also be relevant here since it greatly affects the scope of a variable.

ie what is the difference between

onclick="js();" and onclick="js;" or onclick="js"

where JS is a defined Java Script function.

Answer 1

Change your code like this.

var timeline,changer;
function startloop()
{
    changer = setInterval("changecontents();", 2000);
    timeline = setInterval("change();", 2000);  
}

window.onload = startloop();

function arrow_onmouseover()
{ 
window.clearInterval(timeline);
window.clearInterval(changer);
}

The difference between

onclick=”js();” and onclick=”js;” or onclick=”js”

if your js function doesn’t have any parameters to receive you can simple avoid () like if you want to get the date you can call new Date(); but instead you can simply call new Date;