Javascript Argument

Question

I type in scroll(0,10,200,10); But when it runs it passes the string "xxpos" or "yypos" and I did try it without the appostraphes, but it just didn't work.

scroll = function(xpos,ypos,time,rounds){
 var xxpos = xpos*1;
 var yypos = ypos*1;
 var rrounds = rounds*1;
 var ttime = time*1;
 x = 0;
 xyz=window.setInterval("scroller('xxpos','yypos','ttime','rrounds')",ttime);
}
function scroller(xpos,ypos,time,rounds){
 alert(xpos + ypos + time + rounds);
}

• Niklas R: You give the scroller function strings as parameters. Also, afaik, the variables won't be available from the scope setInterval will evaluate the string.
• Rob W: What are the undeclared x = 0 and xyz = .. doing there?
• Gabriel Gartz: Maybe the xyz is a var from another scope that he need's to stop his interval. But the name is ugly.
• Tanner Ellis: The x was in there because I'm using it to see how many times the function has been ran, you just can't see that part and xyz is used to stop it. I'm just learning all of this, so sorry if it looks so horrible. I'm just practicing making a javascript framework in my free time after school.

Answer 1

Don't use strings, use closures (anonymous functions).

window.setTimeout(function() {
 scroller(xxpos, yypos, ttime, rrounds);
}, ttime);

Answer 2

It should be like this:

 xyz=window.setInterval("scroller(" + xxpos + "," + yypos + "...

otherwise you just pass strings xxpos, yypos etc.

• Tanner Ellis: Thanks so much! This worked! I can't believe I didn't think of something so obvious!

Answer 3

do you happen to know that in your code, each call to scroll() builds a timer?

do you mean to do it like it was a loop? then:

xyz = window.setTimeout(function(){
 scroller(xxpos,yypos,ttime,rrounds)
},ttime);

Answer 4

You should use closure:

...
xyz = window.setInterval(function() { scroller(xxpos,yypos,ttime,rrounds); }, ttime);
...

Answer 5

That's because the string does not become the variable.

This would work:

window.setInterval("scroller("+ xxpos + "," + yypos + "," + ttime + "," + rrounds + ")",ttime);

Or better:

window.setInterval(function() { scroller(xxpos, yypos, ttime, rrounds); }, ttime);