Hi @trickroll and thanks for the contribution! I am not sure which rule you applied for deciding between let and const. Normally you should use const whenever possibly and only use let if it is not possible otherwise.

@Corvince Thank you for feedback! Let me revisit the const vs let. Apologies about the thrash and appreciate the patience. Understand that there are benefits to making variables immutable

Everything else looks good to me.
Make sure to:

• Squash the commits into 1 commit
• Use imperative voice when writing the commit message, i.e. "refactor: Replace var with const/let in some JS files". You can edit a commit's message by doing git commit --amend. examples: correcting comment in examples/pd_grid/pd_grid/agent.py #1247 (comment) has a guide on this

If you want to programmatically catch these reassignment errors, you can use eslint.
After installing, you need to create .eslintrc.js in the root of your Git repo, containing this:

module.exports = {
    "env": {
        "browser": true,
    },
    "extends": "eslint:recommended",
    "parserOptions": {
        "ecmaVersion": 12
    },
    "rules": {
    }
};

It should tell you this error if you specify svg_tag as const while doing the +=:

15:5   error  'svg_tag' is constant                                no-const-assign

Pinging @SangameshItagi because this info is useful for him as well.

@rht - Thank you for your guidance and support! Makes a huge difference for a beginner :)

LGTM

Merged, thank you!