Does element.replaceChildren() function work with duplicate values, or what is stopping this from working

currently i am trying to replace an elements children with the same value in an array
e.g:

const e = document.createElement("div");
e.className = "e";
e.innerHtml = "test ";
const a = [e, e, e];
// test is appearing only once instead of multiple times
document.body.replaceChildren(...a);

my code is this:

    class MockElement {
        constructor(className, children = []) {
            this.element = document.createElement("div");
            this.className = className;
            this.children = children;
            this.element.className = className;
            console.log(Array(children))
            if (children) this.element.replaceChildren(...Array(children));
        };
        replaceChildren(c) {
            this.children = c;
            this.element.replaceChildren(...c);
        };
    };

    //const wrapper = document.getElementById("centirdle-boards");



    const fill = (c, t) => {
        // init new array
        let a = new Array();
        // loop through {t} times, adds new copy of {c} to the array each time
        for (let j = 0; j < t; j++) a.push( c );
        return a;
    };

    const h = new MockElement("h");
    // only seeing one of them
    document.body.replaceChildren(...fill(h.element, 5))

currently the fill function works fine and as intended
the mock element class also works fine

Answer

JavaScript objects are references. This means that there is only a single h.element in the memory of your whole program, so if you tell the DOM to replace children with h.element 5 times, it will only insert it once because it is five references to a single element.

You must create multiple elements.

With your code example, that would look like this:

// Calls `document.createElement` five times total
const elements = new Array(5)
  .fill(null)
  .map(() => new MockElement("h").element); 

document.body.replaceChildren(...elements);

Check out this article to learn more: https://dmitripavlutin.com/value-vs-reference-javascript/