GetElementByID - Multiple IDs

document.getElementById() only supports one name at a time and only returns a single node not an array of nodes. You have several different options:

1. You could implement your own function that takes multiple ids and returns multiple elements.
2. You could use document.querySelectorAll() that allows you to specify multiple ids in a CSS selector string .
3. You could put a common class names on all those nodes and use document.getElementsByClassName() with a single class name.

Examples of each option:

doStuff(document.querySelectorAll("#myCircle1, #myCircle2, #myCircle3, #myCircle4"));

or:

// put a common class on each object
doStuff(document.getElementsByClassName("circles"));

or:

function getElementsById(ids) {
    var idList = ids.split(" ");
    var results = [], item;
    for (var i = 0; i < idList.length; i++) {
        item = document.getElementById(idList[i]);
        if (item) {
            results.push(item);
        }
    }
    return(results);
}

doStuff(getElementsById("myCircle1 myCircle2 myCircle3 myCircle4"));

This will not work, getElementById will query only one element by time.

You can use document.querySelectorAll("#myCircle1, #myCircle2") for querying more then one element.

ES6 or newer

With the new version of the JavaScript, you can also convert the results into an array to easily transverse it.

Example:

const elementsList = document.querySelectorAll("#myCircle1, #myCircle2");
const elementsArray = [...elementsList];

// Now you can use cool array prototypes
elementsArray.forEach(element => {
    console.log(element);
});

How to query a list of IDs in ES6

Another easy way if you have an array of IDs is to use the language to build your query, example:

const ids = ['myCircle1', 'myCircle2', 'myCircle3'];
const elements = document.querySelectorAll(ids.map(id => `#${id}`).join(', '));