Truthy vs Falsy Values, Explicit Type Conversion

Truthy vs Falsy Values:

Falsy Values :

• "",'' String with zero length
• false- boolean keyword
• 0 number zero, -0 negative zero, 0n bigint zero.
• NaN-Not a Number
• null
• undefined- Variable that has been declared but not assigned with a value.

Truthy Values :

• Everything else Truthy.

function isFalsy(value) {
    if(value) {
        console.log ("The value is truthy.");
    } else {
        console.log ("The value is falsy.");
    }
}

isFalsy(false); //falsy value
isFalsy(0);     //falsy value
isFalsy(-0);    //falsy value
isFalsy(0n);    //falsy value
isFalsy(null);  //falsy value
isFalsy(undefined); //falsy value
isFalsy(NaN);    //falsy value
isFalsy("");    //falsy value
isFalsy('');    //falsy value
isFalsy(``);    //falsy value
isFalsy(1);     //truthy value
isFalsy(-1);    //truthy value
isFalsy(0.1);   //truthy value
isFalsy(-0.1);  //truthy value
isFalsy(1n);    //truthy value
isFalsy("false"); //truthy value
isFalsy("0");    //truthy value 
isFalsy("null"); //truthy value
isFalsy("undefined"); //truthy value
isFalsy("NaN");  //truthy value

Explicit Type Conversion :

• It is used to manually convert a value from one data type to another using build-in functions.

Converting to String :

• string(value)
• .toString(value)

let a = 10;
console.log(typeof a); // number
console.log(typeof String(a)); // string
console.log(typeof a.toString()); // string

Converting to Number :

• Number(value)
• parseInt(value)
• parseFloat(value)
• Using unary +

let a ="10";
let b ="10.5";
console.log(typeof a); // string
console.log(typeof Number(a)); // number
console.log(typeof parseInt(a)); // number
console.log(typeof parseFloat(b)); // number


console.log(5+"10"); // string concatenation, result is "5" + "10" = "510"

// If one value is a string, + becomes string concatenation, not addition. Only + behaves differently , others (-, *, /) convert to numbers.

// Using unary + we can convert string to numeric.
console.log(5+ +"10"); // numeric addition, +"10" converts "10" to 10, result is 5 + 10 = 15


console.log(5-"10"); // numeric subtraction, "10" is converted to 10, result is 5 - 10 = -5
console.log(5*"10"); // numeric multiplication, "10" is converted to 10, result is 5 * 10 = 50
console.log(5/"10"); // numeric division, "10" is converted to 10, result is 5 / 10 = 0.5

Converting to Boolean :

• Converts a value to true or false based on its truthiness
  • Falsy values (become false): 0, "" (empty string), null, undefined, NaN, and false.
  • Truthy values (become true): Everything else, including "0", "false", "null", "undefined", "NaN".