Hands-on

• Create const name = "Aarav", const age = 22, const city = "Jaipur".
• Build the string "Aarav, 22, from Jaipur" using old-style concatenation with +.
• Build the same string using a template literal.
• Then build a 3-line “card” with a multi-line template literal:
  • Line 1: Name: <name>
  • Line 2: Age: <age>
  • Line 3: City: <city>

const name = "Aarav";
const age = 22;
const city = "Jaipur";

const oldStyle = name + ", " + age + ", from " + city;
console.log(oldStyle);

const templateStyle = `${name}, ${age}, from ${city}`;
console.log(templateStyle);

const card = `
Name: ${name}
Age: ${age}
City: ${city}
`;
console.log(card);

Open the console (F12). This matches ../js/hands-on.js (loaded below).

• Declare let user; (no value). Log it. Log typeof user.
• Set user = null. Log it. Log typeof user.
• Compare null == undefined and null === undefined. Note the difference.
• In a comment, explain when you should use null vs leave it undefined.

let user;

console.log(user); // undefined
console.log(typeof user); // "undefined"

user = null;

console.log(user); // null
console.log(typeof user); // "object"

console.log(null == undefined); // true
console.log(null === undefined); // false

// Use null when you intentionally mean "no value" (cleared field, API placeholder).
// Leave undefined for "not assigned yet" — optional props, declare-before-assign.

Same behaviour in ../js/hands-on.js.

• Compute 0.1 + 0.2. Log the result.
• Compare it to 0.3 with ===. Note the surprise.
• Try Number.isInteger(5), Number.isInteger(5.0), Number.isInteger(5.5).
• Try 1 / 0 and "abc" * 2. Note the special values.

console.log(0.1 + 0.2);
console.log((0.1 + 0.2) === 0.3);

console.log(Number.isInteger(5));
console.log(Number.isInteger(5.0));
console.log(Number.isInteger(5.5));

console.log(1 / 0);
console.log("abc" * 2);

Same behaviour in ../js/hands-on.js.