Section 1.1: Variable Declaration Made Simple

In JavaScript, you typically declare variables using the let keyword. If you declare a variable without an initial value, it will be undefined:

let a = 30;

let b = 100;

let c;

console.log(a, b, c); // Output: 30 100 undefined

You can condense the declaration of multiple variables into a single line:

let a = 30, b = 100, c;

console.log(a, b, c); // Output: 30 100 undefined

Alternatively, you can use array destructuring for a more elegant approach:

let [a, b, c] = [30, 100];

console.log("value of a", a); // Output: value of a 30

console.log("value of b", b); // Output: value of b 100

console.log("value of c", c); // Output: value of c undefined

Section 1.2: The Ternary Operator

A common use of JavaScript is conditional statements. Instead of using the traditional if...else, you can employ the ternary operator for conciseness:

const result = (num === 2) ? "Hello" : "Number not 2";

This single line effectively replaces the longer if...else structure. For example:

const rank = 59;

return (rank <= 10) ? "Good rank" : "Bad rank";

Section 1.3: Short-Circuit Evaluation

Assigning one variable to another is often done with checks for null or undefined values. Instead of a verbose if statement, you can leverage short-circuit evaluation:

let var2 = var1 || "hello";

In this example, var2 will take the value of var1 unless it is falsy, in which case it defaults to "hello".

Section 1.4: Swapping Variables

Swapping values between two variables can be simplified without the need for a temporary variable:

let a = 8, b = 48;

[a, b] = [b, a];

This method is both efficient and clean.

Section 1.5: Arrow Functions for Simplicity

Arrow functions allow you to define functions more succinctly, omitting the function keyword:

const multiply = (a, b) => a * b;

For complex functions, you can still use curly braces:

const dis = (a1, b1, a2, b2) => {

let a = b1 - a1;

let b = b2 - a2;

return Math.sqrt(a * a + b * b);

};

Section 1.6: Enhanced String Interpolation

With ES6 template literals, string concatenation becomes much cleaner:

console.log(Hello, I obtained a rank of ${rank} in this ${year});

This method eliminates cumbersome string concatenation using the + operator.

Section 1.7: Using the Exponent Operator

Instead of Math.pow(), you can use the exponentiation operator **:

console.log(7 ** 2); // Output: 49

console.log(4 ** 0.5); // Output: 2

Section 1.8: The Spread Operator

Finding the maximum or minimum in an array can be done easily with the spread operator:

const abc = [4, 8, 12, 27, 2, 7];

console.log(Math.max(...abc)); // Output: 27

console.log(Math.min(...abc)); // Output: 2

You can also concatenate arrays effortlessly:

const mnp = [...abc, ...xyz];

Section 1.9: Boolean Conversion

To convert any value to a boolean, use double exclamation marks:

console.log(!!0); // Output: false

console.log(!!""); // Output: false

Section 1.10: Shortening Loops

Instead of traditional for loops, consider using for...of or forEach() for cleaner iteration:

numberList.forEach(value => console.log(value));

Section 1.11: Rounding Numbers

You can round numbers without Math.floor() by using the bitwise NOT operator:

const rounded = ~~7.89; // Output: 7

Section 1.12: Object Property Shorthand

When the variable names match the object keys, you can simplify object creation:

let Details = { bookName, bookAuthor };

Section 1.13: Decimal Exponents

Using decimal base exponents can simplify loops:

for (let i = 0; i < 1e5; i++) {

// Do something

}