Resolve LGTM errors

[lisaychuang]

Resolve LGTM errors (see LGTM alert snapshot here):

• Added let variable declaration in for...in statements, line 151 & line 152
• Update all variable declarations from var to let

[lisaychuang]

Resolve LGTM errors in analysis.js file, see LGTM alert snapshot here

• Update all variable declarations from var to let
• Removed unused variables: test, percent in analyse() function
• Added let variable declaration in for...in statements, line 55,56,59
• Added let variable declaration for tr_ew (line 107), tr_ewm (line 117)

[lisaychuang]

@selfthinker please review when you get a chance!