Fix LGTM alerts

[lisaychuang]

Hi @jdetaeye, I've referenced LGTM alert snapshot page and fixed two categories of errors:

• Added var declaration to variables
• Added ; semicolons to avoid automated semicolon insertion

Please review when you get a chance, thanks!

[lisaychuang]

Commit 55c029e, see LGTM alert snapshot for details:

• Fix error for elements with duplicate id attributes.

[lisaychuang]

Commit bda01e0, see LGTM alert snapshot for details:

• Added var declaration to variables
• Fix typeof error for string

[lisaychuang]

Commit e5a7f8e, see LGTM alert snapshot for details:

• Changed multi-line strings from string concatenation + to ES6 template literals using backticks `

[lisaychuang]

Commit f560ebc, see LGTM alert snapshot for details:

• Move variable declaration to top of function scope before use in if statements

[jdetaeye]

The changes from f560ebc are in a third-party library. I prefer not to modify it.

The changes from 55c029e
will be included. We actually don't need the id of these elements anyway, so I'll just remove those.

The changes from bda01e0 will be included as you suggest, except for the one on line 71.

The LGTM changes will be reviewed one by one, but look good to me.

Much appreciate the input! Thanks.

[lisaychuang]

@jdetaeye that sounds great, thank you for taking the time to review my commits. I'm glad I could help contribute to frePPle! Thank you for all your hard work maintaining this library!

[jdetaeye]

Closing this one. Too many false positives, and low priority to correct all this.