javascript help needed.

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MrAlan

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#29358 4-Jan-2009 20:14

Hi guys, I'm not very familiar with JavaScript. Is there any way of doing the following with Javascript?

var x = document;
var y = .write;
var c = x+y;
c("Hello World!");

RedJungle

Phil Gale
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Red Jungle

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#187362 4-Jan-2009 20:23

You want to combine two variables and then be able to call that variable as if it were a function? or you want to be able to write some output somewhere?

Perhaps if you can tell me more about what you're trying to achieve I might be able to suggest a better/more useful solution?

Ragnor

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#187365 4-Jan-2009 20:36

Yeah what RedJungle said, what are you trying to do? It's pretty rare to write directly to the document thesedays, normally if you want to insert content into the page via javascript you'd have a div tag and use javascript to find that element in the document object model via id or class then insert content into the div.

MrAlan

98 posts

Master Geek

#187387 4-Jan-2009 21:38

well that was just an example. I am wondering if I can put two variables together to perform a command.

I have a function which creates a layer and brings up a bunch of colours to choose from. Depending on the arguments I pass to that function I want it to change what action it performs. i.e (with another simplified example)

I have a button called [change text colour] and onclick it calls my color function and sends 3 arguments "window.mytext", ".style.color" and "#FFFFFF". I also have a button called change [background colour] and it also passes 3 arguments "window.divbgcolour", ".style.backgroundColor" and "#000000".

so I want my function to do this:

function setcolor(inputobj, inputstyle, colour) {
inputobj+inputstyle = colour;
}

so far I've had no luck with making that work. I can however get it to work this way:

function setcolor(inputobj, inputstyle, colour) {
if (inputstyle == '.style.backgroundColor') {
inputobj.style.backgroundColor = colour;
}
if (inputstyle == '.style.color') {
inputobj.style.color = colour;
}
}

RedJungle

Phil Gale
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#187397 4-Jan-2009 22:07

I get what you're after. Sadly, I think your current approach is as close as you'll get really.

By the looks of things, the first parameter 'inputobj' is a reference to the actual DOM object you want so you're able to access it fine. But for 'inputstyle', unless you pass a reference to the actual object (which would defeat the objective I imagine), its just going to be interpretted as a string.

I would probably take a similar approach using if/switch statements to handle each case.

nate

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#187410 5-Jan-2009 00:09

The eval() function evaluates a string and executes it as if it was script code.

Concatenate what you are trying to do together, then pass it to eval.

sleemanj

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#187418 5-Jan-2009 01:22

function setcolor(inputobj, inputstyle, colour) {
inputobj+inputstyle = colour;
}

Use the associative array syntac for object referencing.

function setcolor(inputobj, property, colour) {
inputobj.style[property] = colour;
}

setcolor(document.getElementById('something'), 'backgroundColor', '#EFEFEf');

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RedJungle

Phil Gale
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#187439 5-Jan-2009 09:21

nate: The eval() function

Ha! Forgot about that one. Nate's onto it.

MrAlan

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#187595 5-Jan-2009 17:15

thanks for all the help.I'll give the eval() function a go tonight.

Ragnor

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#187610 5-Jan-2009 18:13

sleemanj:

Use the associative array syntac for object referencing.

function setcolor(inputobj, property, colour) {
inputobj.style[property] = colour;
}

setcolor(document.getElementById('something'), 'backgroundColor', '#EFEFEf');

This way is recommend way over using Eval in this situation imo

Refer to: http://24ways.org/2005/dont-be-eval