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JavaScript Strict Mode

Strict mode enforces a stricter set of rules in JavaScript, catching common mistakes, disallowing certain features, and improving code safety and performance.

Key Topics

Enabling Strict Mode

Add "use strict"; at the beginning of a script or function to enable strict mode.

Key Restrictions

Strict mode disallows undeclared variables, duplicate parameter names, and certain octal syntax, among other things.

Benefits

Strict mode helps avoid silent errors, makes debugging easier, and can enable certain optimizations in JS engines.

"use strict";
// x = 10; // ReferenceError in strict mode
let x = 10;
console.log(x);

Explanation: Without let or var, x would fail, but in strict mode it throws an error instead of creating a global variable silently.

JavaScript Usage in DOM

Use strict mode in DOM scripts to ensure cleaner, error-free code when manipulating elements and handling events.

Key Takeaways

  • Enable Strict: Add "use strict" at start of file or function.
  • Disallows Undeclared Vars: Catches common errors early.
  • Better Debugging: More errors are thrown instead of silent fails.
  • DOM Integration: Ensures robust, maintainable scripts.
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