Bagaimana Anda memeriksa apakah nilai boolean benar atau salah dalam javascript?

Boolean adalah tipe data yang mengembalikan salah satu dari dua nilai i. e. benar atau salah. Dalam JavaScript, Boolean digunakan sebagai fungsi untuk mendapatkan nilai variabel, objek, kondisi, ekspresi, dll. dalam hal benar atau salah

Catatan. Variabel atau objek yang memiliki nilai diperlakukan sebagai nilai boolean sejati. '0', 'NaN', string kosong, 'undefined', dan 'null' diperlakukan sebagai nilai boolean palsu.  

Di sini a1 dan a2 menyimpan nilai boolean i. e. benar dan salah masing-masing.  

var a1 = true;
var a2 = false;

Catatan. Variabel di bawah ini diinisialisasi dengan string bukan nilai boolean.   

var a1 ="true";
var a2 ="false";

Boolean() fungsi dalam JavaScript. Fungsi Boolean mengembalikan nilai boolean dari variabel. Itu juga dapat digunakan untuk menemukan hasil boolean dari suatu kondisi, ekspresi, dll

Sintaksis.   

Boolean(variable/expression) 

Objek JavaScript Boolean. Objek boolean dalam javascript adalah pembungkus objek untuk nilai boolean. Boolean dalam JavaScript juga dapat didefinisikan menggunakan kata kunci baru.  

Sintaksis.   

new Boolean(value)

Di bawah ini adalah contoh metode JavaScript Boolean

Contoh 1. Program di bawah ini akan memberikan nilai sebenarnya sebagai output

javascript

function

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

Keluaran.  

true

Contoh 2

Javascript

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

Boolean(variable/expression) 

Boolean(variable/expression) 

Boolean(variable/expression) 

Boolean(variable/expression) 

var a1 ="true";
var a2 ="false";

Boolean(variable/expression) 

Boolean(variable/expression) 

var a1 ="true";
var a2 ="false";

Boolean(variable/expression) 

Boolean(variable/expression) 

var a1 ="true";
var a2 ="false";

new Boolean(value)

Boolean(variable/expression) 

new Boolean(value)

Boolean(variable/expression) 

var a1 ="true";
var a2 ="false";

new Boolean(value)

Boolean(variable/expression) 

new Boolean(value)

Boolean(variable/expression) 

var a1 ="true";
var a2 ="false";

true

Boolean(variable/expression) 

true

var a1 ="true";
var a2 ="false";

true

true

Keluaran.  

Boolean(10) is true
Boolean("GeeksforGeeks") is true
Boolean(2.74) is true
Boolean(-1) is true
Boolean('true') is true
Boolean('false') is true
Boolean(3 * 2 + 1.11) is true
Boolean(1<2) is true

Contoh 3. Program di bawah ini akan memberikan nilai palsu sebagai output.   

javascript

true

true

true

var a1 ="true";
var a2 ="false";

Boolean(10) is true
Boolean("GeeksforGeeks") is true
Boolean(2.74) is true
Boolean(-1) is true
Boolean('true') is true
Boolean('false') is true
Boolean(3 * 2 + 1.11) is true
Boolean(1<2) is true

Boolean(10) is true
Boolean("GeeksforGeeks") is true
Boolean(2.74) is true
Boolean(-1) is true
Boolean('true') is true
Boolean('false') is true
Boolean(3 * 2 + 1.11) is true
Boolean(1<2) is true

var a1 ="true";
var a2 ="false";

Boolean(10) is true
Boolean("GeeksforGeeks") is true
Boolean(2.74) is true
Boolean(-1) is true
Boolean('true') is true
Boolean('false') is true
Boolean(3 * 2 + 1.11) is true
Boolean(1<2) is true

Boolean(variable/expression) 

Boolean(10) is true
Boolean("GeeksforGeeks") is true
Boolean(2.74) is true
Boolean(-1) is true
Boolean('true') is true
Boolean('false') is true
Boolean(3 * 2 + 1.11) is true
Boolean(1<2) is true

Boolean(variable/expression) 

var a1 ="true";
var a2 ="false";

Boolean(10) is true
Boolean("GeeksforGeeks") is true
Boolean(2.74) is true
Boolean(-1) is true
Boolean('true') is true
Boolean('false') is true
Boolean(3 * 2 + 1.11) is true
Boolean(1<2) is true

Boolean(variable/expression) 

Boolean(0) is false
Boolean("") is false
Boolean(e) undefined is false
Boolean(-0) is false
Boolean(false) is false
Boolean(NaN) is false
Boolean(null) is false
Boolean(1>2) is false

var a1 ="true";
var a2 ="false";

Boolean(0) is false
Boolean("") is false
Boolean(e) undefined is false
Boolean(-0) is false
Boolean(false) is false
Boolean(NaN) is false
Boolean(null) is false
Boolean(1>2) is false

Boolean(0) is false
Boolean("") is false
Boolean(e) undefined is false
Boolean(-0) is false
Boolean(false) is false
Boolean(NaN) is false
Boolean(null) is false
Boolean(1>2) is false

var a1 ="true";
var a2 ="false";

Boolean(0) is false
Boolean("") is false
Boolean(e) undefined is false
Boolean(-0) is false
Boolean(false) is false
Boolean(NaN) is false
Boolean(null) is false
Boolean(1>2) is false

Boolean(variable/expression) 

Boolean(0) is false
Boolean("") is false
Boolean(e) undefined is false
Boolean(-0) is false
Boolean(false) is false
Boolean(NaN) is false
Boolean(null) is false
Boolean(1>2) is false

Boolean(variable/expression) 

var a1 ="true";
var a2 ="false";

v1 = false
v2 = false
v3 = false
v4 = false
v5 = true
v6 = true

v1 = false
v2 = false
v3 = false
v4 = false
v5 = true
v6 = true

var a1 ="true";
var a2 ="false";

v1 = false
v2 = false
v3 = false
v4 = false
v5 = true
v6 = true

Boolean(variable/expression) 

v1 = false
v2 = false
v3 = false
v4 = false
v5 = true
v6 = true

Boolean(variable/expression) 

var a1 ="true";
var a2 ="false";

v1 = false
v2 = false
v3 = false
v4 = false
v5 = true
v6 = true

v1 = = v2 is true
v1 = = = v2 is false

Keluaran.  

Boolean(0) is false
Boolean("") is false
Boolean(e) undefined is false
Boolean(-0) is false
Boolean(false) is false
Boolean(NaN) is false
Boolean(null) is false
Boolean(1>2) is false

Contoh 4.   

javascript

true

v1 = = v2 is true
v1 = = = v2 is false

Boolean(0) is false
Boolean("") is false
Boolean(e) undefined is false
Boolean(-0) is false
Boolean(false) is false
Boolean(NaN) is false
Boolean(null) is false
Boolean(1>2) is false

v1 = = v2 is true
v1 = = = v2 is false

true

v1 = = v2 is true
v1 = = = v2 is false

v1 = = v2 is true
v1 = = = v2 is false

v1 = = v2 is true
v1 = = = v2 is false

Boolean(0) is false
Boolean("") is false
Boolean(e) undefined is false
Boolean(-0) is false
Boolean(false) is false
Boolean(NaN) is false
Boolean(null) is false
Boolean(1>2) is false

true

v1 = = v2 is true
v1 = = = v2 is false

v1 = = v2 is true
v1 = = = v2 is false

Boolean(10) is true
Boolean("GeeksforGeeks") is true
Boolean(2.74) is true
Boolean(-1) is true
Boolean('true') is true
Boolean('false') is true
Boolean(3 * 2 + 1.11) is true
Boolean(1<2) is true

true

v1 = = v2 is true
v1 = = = v2 is false

var a1 ="true";
var a2 ="false";

true

var a1 ="true";
var a2 ="false";

v1 = = v2 is true
v1 = = = v2 is false

v1 = = v2 is true
v1 = = = v2 is false

var a1 ="true";
var a2 ="false";

true

var a1 ="true";
var a2 ="false";

v1 = = v2 is true
v1 = = = v2 is false

v1 = = v2 is true
v1 = = = v2 is false

Boolean(variable/expression) 

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

Keluaran.   

v1 = false
v2 = false
v3 = false
v4 = false
v5 = true
v6 = true

Contoh 5.   

javascript

true

v1 = = v2 is true
v1 = = = v2 is false

var a1 ="true";
var a2 ="false";

v1 = = v2 is true
v1 = = = v2 is false

true

v1 = = v2 is true
v1 = = = v2 is false

v1 = = v2 is true
v1 = = = v2 is false

v1 = = v2 is true
v1 = = = v2 is false

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

var a1 ="true";
var a2 ="false";

Keluaran.  

v1 = = v2 is true
v1 = = = v2 is false

Catatan. v1 = = = v2 tidak benar karena jenis v1 dan v2(objek) tidak sama

Browser yang Didukung

• Google Chrome 6 dan yang lebih baru
• Tepi 12 ke atas
• Firefox 4 ke atas
• Internet Explorer 9 dan yang lebih baru
• Opera 12 ke atas
• Safari 5. 1 dan di atas

Kami memiliki Lembar Curang tentang Javascript di mana kami membahas semua topik penting Javascript untuk memeriksanya, silakan buka Lembar Curang Javascript-A Panduan dasar untuk JavaScript

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