411 REFERENCE · Wikibooks
Programming Fundamentals/Variable Examples JavaScript
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
Overview
The following examples demonstrate data types, arithmetic operations, and input in JavaScript.
Data Types
// This program demonstrates variables, literal constants, and data types.
var n;
var s;
var b;
n = 1.23456789012345;
s = "string";
b = true;
output("Number n = " + n);
output("String s = " + s);
output("Boolean b = " + b);
function output(text) {
if (typeof document === 'object') {
document.write(text);
}
else if (typeof console === 'object') {
console.log(text);
}
else {
print(text);
}
}
Output
Number n = 1.23456789012345
String s = string
Boolean b = true
Discussion
Each code element represents:
// begins a comment
var n, s, and b define variables
; ends each line of JavaScript code
i = , d = , s =, b = assign literal values to the corresponding variables
output() calls the output function
function output(text) defines a output function that checks the JavaScript environment and writes to the current document, the console, or standard output as appropriate.
Arithmetic
// This program demonstrates arithmetic operations.
var a;
var b;
a = 3;
b = 2;
output("a = " + a);
output("b = " + b);
output("a + b = " + (a + b));
output("a - b = " + (a - b));
output("a * b = " + a * b);
output("a / b = " + a / b);
output("a % b = " + (a % b));
function output(text) {
if (typeof document === 'object') {
document.write(text);
}
else if (typeof console === 'object') {
console.log(text);
}
else {
print(text);
}
}
Output
a = 3
b = 2
a + b = 5
a - b = 1
a * b = 6
a / b = 1.5
a % b = 1
Discussion
Each new code element represents:
+, -, *, /, and % represent addition, subtraction, multiplication, division, and modulus, respectively.
Temperature
// This program converts an input Fahrenheit temperature to Celsius.
var fahrenheit;
var celsius;
output("Enter Fahrenheit temperature:");
fahrenheit = input();
celsius = (fahrenheit - 32) * 5 / 9;
output(fahrenheit.toString() + "° Fahrenheit is " + celsius + "° Celsius");
function input(text) {
if (typeof window === 'object') {
return prompt(text)
}
else if (typeof console === 'object') {
const rls = require('readline-sync');
var value = rls.question(text);
return value;
}
else {
output(text);
var isr = new java.io.InputStreamReader(java.lang.System.in);
var br = new java.io.BufferedReader(isr);
var line = br.readLine();
return line.trim();
}
}
function output(text) {
if (typeof document === 'object') {
document.write(text);
}
else if (typeof console === 'object') {
console.log(text);
}
else {
print(text);
}
}
Output
Enter Fahrenheit temperature:
100
100° Fahrenheit is 37.7777777777778° Celsius
Discussion
Each new code element represents:
function input(text) defines a function that checks the JavaScript environment and reads from the current window, the console, or standard input as appropriate.
References
Wikiversity: Computer Programming