javascript - How can I pass an array of strings to a function as arguments? - Stack Overflow

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I have a couple of arrays, like so:

var galImgs = ["/gallery/image-001.jpg",
               "/gallery/image-002.jpg",
               "/gallery/image-003.jpg"],
    preloadImgs = [];

And I'd like to use a simple for loop to load images from the values in the galImgs array, like so:

function preload() {
    for (i = 0; i < preload.arguments.length; i++) {
    preloadImgs[i] = new Image();
    preloadImgs[i].src = preload.arguments[i];
    }
}

However, calling

preload(galImgs);

passes in the array as a single string, instead of ma-separated strings. How can I pass the galImgs array so it will be read as individual arguments?

I have a couple of arrays, like so:

var galImgs = ["http://domain.tld/gallery/image-001.jpg",
               "http://domain.tld/gallery/image-002.jpg",
               "http://domain.tld/gallery/image-003.jpg"],
    preloadImgs = [];

And I'd like to use a simple for loop to load images from the values in the galImgs array, like so:

function preload() {
    for (i = 0; i < preload.arguments.length; i++) {
    preloadImgs[i] = new Image();
    preloadImgs[i].src = preload.arguments[i];
    }
}

However, calling

preload(galImgs);

passes in the array as a single string, instead of ma-separated strings. How can I pass the galImgs array so it will be read as individual arguments?

• javascript
• arrays
• string

Share Improve this question Follow asked Jul 6, 2011 at 15:14 Isaac LubowIsaac Lubow 3,57355 gold badges4040 silver badges5757 bronze badges 1

• 2 why don't you declare the function with a galImgs parameter? function preload(galImgs) { ... } – Nalum Commented Jul 6, 2011 at 15:18

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4 Answers 4

Sorted by: Reset to default 5

However, calling

preload(galImgs);

passes in the array as a single string, instead of ma-separated strings.

No, it passes in the array, not a string. You've actually gone to too much trouble in your preload function, just use the array you were given:

function preload(a) {
    for (i = 0; i < a.length; i++) {
        preloadImgs[i] = new Image();
        preloadImgs[i].src = a[i];
    }
}

(And declare the i variable within the function, which I haven't added above; as it is, you're falling prey to The Horror of Implicit Globals.)

This has the advantage of not using the arguments pseudo-array, which is a performance hit on most implementations.

If you want, though, you can use an array to pass discrete arguments to preload, via the apply function:

preload.apply(undefined, galImgs);

The first argument is used for this within the function, you can just use undefined for the default; the second argument is the array, which will show up in the function as discrete arguments.

The problem is your using the arguments keyword to find the passed in event. What you really want is

function preload(images) {
    for (i = 0; i < images.length; i++) {
    preloadImgs[i] = new Image();
    preloadImgs[i].src = images[i];
    }
}

To help you understand better, your old way was fine except one thing..

preload.arguments.length == 1
preload.arguments[0] == galImgs
preload.arguments[0][0] == galImgs[0]

You are looking for the apply method:

preload.apply(null, galImgs);

Should do it!

There's nothing to worry about having viewing it as a single string. Just by providing index to your array, you would be able to get the individual strings.

galImgs[0] would return you the string "http://domain.tld/gallery/image-001.jpg"

You can use gallmgs is an array object and you would have all the accessors of an array in this. Try gallmgs.length.

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