JS variable assigned a value is always undefined in Microsoft Edge, but not in Google Chrome

Question

I am encountering an issue where a variable is assigned a value, but the value is always undefined in Microsoft Edge. Strangely, the same code works as expected in Google Chrome. I have confirmed the assigned value is not undefined, and checked that the code does not have any way to assign undefined to the variable. Even though hovering over the variable in DevTools shows the correct value, evaluating the variable in the console still results in undefined. Here is the relevant code:

customElements.define("popup-page", class extends HTMLElement {
    // ...
    #lastDownload = 0;
    // ...

    async #download() {
        // ...
        this.#lastDownload = 0;
        // ...

            for (let i = 0; i < urls.length; i++) {
                // ...
                const id = el.downloadId = await this.#attemptItemAsync(url, maxCon, addDelay);
            }
    }

async #attemptItemAsync(url, maxCon, addDelay) {
        try {
            if (addDelay > 0) {
                const now = Date.now();
                if (now - this.#lastDownload < addDelay) {
                    await sleepAsync(now - this.#lastDownload);
                }
                this.#lastDownload = now;
            }
            
            // ...
        }
        catch {
            return;
        }
    }
});

I believe this is a bug in Microsoft Edge. When I sideloaded the same extension into Google Chrome, the bug did not occur. Please let me know if you need more information.

Answer 1

Hi @Luke Vo,

Thank you for the code. I can successfully reproduce this problem on every channel of Microsoft Edge, but not on Chrome. To me it seems to be a problem that is unknown to Dev Team since higher versions of Edge still has this problem. You can stick to the quick fix first, and submit feedback here to make Dev Team aware of this issue. Hopefully they will bring the change to the next releases.

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Shijie Li