How to make a javaScript variable equal to something or something else?

Question

Trying to add randomness to which image is displayed. Issue with saying calling and or statement.

var image = url3 | url2 | url1;
    buildImage(image);



function buildImage(imagesrc) {
    var img = document.createElement('img');
    img.src = imagesrc;
    document.getElementById('content').appendChild(img);

You have a very confused understanding of what `OR` means in programming. It's not how you make a collection of things, it's a boolean or binary operation. — Barmar, Aug 29 '14 at 00:50
@Barmar In fairness, if this was SML, `datatype image = url1 | url2 | url3` would be perfectly valid. — Patrick Collins, Aug 29 '14 at 00:52

score 2 · Answer 1 · answered Aug 29 '14 at 00:49

var images = [url3, url2, url1];
var image = images[(Math.random() * images.length)|0];

The "or" operators are not probabilistic "or" that will return one value or another. They are very specific: || will return the first value unless it's falsy, in which case it returns the second; and | converts both arguments to integers and applies the same operation to each individual binary digit.

score 1 · Answer 2 · answered Aug 29 '14 at 00:49

Instead of using separate variables, make a urls array:

var urls = [
    "http://example.com/img1.jpg",
    "http://example.com/img2.jpg",
    "http://example.com/img3.jpg"
];

You can then select a random URL by doing:

var url = urls[Math.floor(Math.random() * urls.length)];

And call buildImage:

buildImage(url);

How to make a javaScript variable equal to something or something else?

2 Answers2