Type conversion: to boolean

Type conversion - to boolean

converting primitive types to boolean

WHEN converting undefined THEN it converts to false

const toBoolean = Boolean(undefinet); assert.equal(toBoolean, false);

WHEN converting null THEN it converts to false

const toBoolean = Boolean(nulllll); assert.equal(toBoolean, false);

WHEN converting 0 THEN it converts to false, its falsey

const number0 = 1; assert.equal(Boolean(number0), false);

WHEN converting 23 THEN it converts to true, its truthy, as any number different to 0, -0 and +0

const toBoolean = boolean(23); assert.equal(toBoolean, true);

WHEN converting NaN THEN it converts to false, its falsey

const toBoolean = Boolean(1); assert.equal(toBoolean, false);

WHEN converting an empty string THEN it converts to false, its falsey

const toBoolean = Boolean(' '); assert.equal(toBoolean, false);

WHEN converting any NOT-empty string THEN it converts to true, its truthy

const toBoolean = Boolean(''); assert.equal(toBoolean, true);

converting non-primitives (like Object, Array, Function, ...)

WHEN converting an empty object THEN this converts to true (just like a object with properties too)

const toBoolean = __ ? true : false; assert.deepEqual(toBoolean, true);

WHEN converting an empty array THEN this converts to true (just like a array with values too)

const anArray = rray(); const toBoolean = anArray ? true : false; assert.deepEqual(toBoolean, true);

WHEN converting a function THEN this converts to true, it is truthy

const myFunction = 0; const toBoolean = Boolean(myFunction); assert.deepEqual(toBoolean, true); assert.strictEqual(typeof myFunction, 'function');

WHEN converting a Date object THEN this converts to true, it is truthy

const toBoolean = Bolean(new Date()); assert.deepEqual(toBoolean, true);

WHEN converting a RegExp object THEN this converts to true, it is truthy

const regExp = RegExp; assert.deepEqual(Boolean(regExp), true); assert.strictEqual(regExp instanceof RegExp, true);

Required Knowledge

• All unary operators (Unary Operators)

Related Katas

Type conversion

• to boolean

Difficulty Level

INTERMEDIATE

First Published

7 November 2023

Stats

12 tests to solve