Loops can execute a block of code a number of times. Show
JavaScript LoopsLoops are handy, if you want to run the same code over and over again, each time with a different value. Often this is the case when working with arrays: Instead of writing: text += cars[0] + "<br>"; You can write: for (let i = 0; i < cars.length; i++) { Try it Yourself » Different Kinds of LoopsJavaScript supports different kinds of loops:
The For LoopThe for (expression 1; expression 2; expression 3) { Expression 1 is executed (one time) before the execution of the code block. Expression 2 defines the condition for executing the code block. Expression 3 is executed (every time) after the code block has been executed. Example for (let i = 0; i < 5; i++) { Try it Yourself » From the example above, you can read: Expression 1 sets a variable before the loop starts (let i = 0). Expression 2 defines the condition for the loop to run (i must be less than 5). Expression 3 increases a value (i++) each time the code block in the loop has been executed. Expression 1Normally you will use expression 1 to initialize the variable used in the loop (let i = 0). This is not always the case, JavaScript doesn't care. Expression 1 is optional. You can initiate many values in expression 1 (separated by comma): Example for (let i = 0, len = cars.length, text = ""; i < len; i++) { Try it Yourself » And you can omit expression 1 (like when your values are set before the loop starts): Example let i = 2; Try it Yourself » Expression 2Often expression 2 is used to evaluate the condition of the initial variable. This is not always the case, JavaScript doesn't care. Expression 2 is also optional. If expression 2 returns true, the loop will start over again, if it returns false, the loop will end. If you omit expression 2, you must provide a break inside the loop. Otherwise the loop will never end. This will crash your browser. Read about breaks in a later chapter of this tutorial. Expression 3Often expression 3 increments the value of the initial variable. This is not always the case, JavaScript doesn't care, and expression 3 is optional. Expression 3 can do anything like negative increment (i--), positive increment (i = i + 15), or anything else. Expression 3 can also be omitted (like when you increment your values inside the loop): Example let i = 0; Try it Yourself » Loop ScopeUsing Examplevar i = 5; for (var i = 0; i < 10; i++) { // Here i is 10 Try it Yourself » Using Examplelet i = 5; for (let i = 0; i < 10; i++) { // Here i is 5 Try it Yourself » In the first example, using In the second example, using When For/Of and For/In LoopsThe While LoopsThe Bagaimana cara memanggil fungsi di JavaScript?Cara Memanggil/Eksekusi Fungsi
Kita bisa memanggil fungsi di dalam kode Javascript dengan menuliskan nama fungsinya seperti ini: namaFungsi(); Contoh: // membuat fungsi function sayHello(){ console.log("Hello World!"); } // memanggil fungsi sayHello() // maka akan menghasilkan -> Hello World!
Apa itu operator ternary JavaScript?Operator ternary merupakan shorthand untuk percabangan if , tapi lebih singkat dan to the point. Sama seperti if , kita bisa membuat percabangan lebih dari satu kondisi dan lebih dari dua pilihan (aksi).
Apa cara yang benar untuk menulis array JavaScript?Cara Membuat Array pada Javascript
Pada javascript, array dapat kita buat dengan tanda kurung siku ( [...] ). Contoh: var products = []; Maka variabel products akan berisi sebuah array kosong.
Bagaimana cara kita melakukan sebuah operasi perkalian pada JavaScript?Opeartor Aritmatika pada Javascript
Untuk melakukan operasi perkalian, kita menggunakan simbol asterik * . Jangan gunakan x , karena simbol x bukan termasuk dalam operator di dalam pemrograman. Lalu untuk pemangkatan kita menggunakan asterik ganda ** . Untuk pembagian, kita gunakan simbol garis miring / .
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