Bits of .NET

⚡ Strict Mode = Better Code

JavaScript is forgiving. Strict mode is strict. Catch errors early, write better code.

📝 Strict Mode Basics

// Enable for entire script
"use strict";

// Enable for function only
function strictFunction() {
    "use strict";
    // strict code
}

// Examples of strict mode
// 1. Cannot use undeclared variables
// Bad (without strict)
x = 10; // Creates global variable

// Good (strict)
"use strict";
x = 10; // ReferenceError

// 2. Cannot delete variables
"use strict";
var x = 5;
delete x; // SyntaxError

// 3. Duplicate parameter names
// Bad (without strict)
function add(a, a) { return a + a; }

// Good (strict)
"use strict";
function add(a, b) { return a + b; }

// 4. Octal literals
"use strict";
var num = 010; // SyntaxError

// 5. with statement
"use strict";
with (obj) { } // SyntaxError

🎯 Strict Mode Benefits

// 1. Prevents accidental globals
function strictFunction() {
    "use strict";
    undeclared = 5; // ReferenceError
}

// 2. Prevents duplicate property names
"use strict";
var obj = {
    prop: 1,
    prop: 2 // SyntaxError
};

// 3. Prevents octal notation
"use strict";
var num = 012; // SyntaxError

// 4. Prevents delete on variables
"use strict";
var x = 5;
delete x; // SyntaxError

// 5. Makes eval safer
"use strict";
eval('var x = 5');
console.log(x); // ReferenceError

// 6. Prevents this from being global
function strictFunc() {
    "use strict";
    console.log(this); // undefined
}

// 7. Reserves keywords
"use strict";
var private = 5; // SyntaxError

// 8. Improves performance
// Some optimizations enabled

// Strict Mode Tips
- Enable by default
- Prevents common errors
- Catch bugs early
- Better performance
- Essential for modern JS

💡 Strict Mode Tips

• Enable by default
• Prevents common errors
• Catch bugs early
• Better performance
• Essential for modern JS