JavaScript's Slightly Stricter Mode
summary
Strict mode makes JavaScript throw concrete errors instead of silently failing: assigning without var raises a ReferenceError that prevents implicit globals, duplicate function parameters and duplicate object keys become syntax errors, octal literals and delete of locals are illegal, and the problematic with statement and arguments.caller/arguments.callee are disallowed for optimization. Concatenation can accidentally inherit or lose strictness, so wrap each file in an IIFE with "use strict"; to opt in safely and reveal bugs early.
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chapters (7)
- 0:00JavaScript strict mode intro
- 2:55Strict mode prevents globals
- 5:48Strict mode removes features
- 6:32Strict mode performance
- 8:54Strict mode semantics
- 12:33Using strict mode safely
- 13:56Final thoughts
