Mex at 13:23, 14 August 2018

2018-08-14T13:23:58Z

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{{DISPLAYTITLE:JavaScript Tutorial}}
This page shows some of the functionality in JavaScript. Be sure to reference the [https://www.ecma-international.org/publications/standards/Ecma-262.htm official ECMAScript (JavaScript) manual] when you can.
==Comments==
{{JSCode|1=// this is a single line comment, which can appear at the end of any line}} 

{{JSCode|1=/*
this is a multi line comment,
which can appear anywhere
*/
}}</code>

==Functions==

{{JSCode|1=someFunction(); // this is a call to a function named someFunction, the code for that function will run when the function is called}} 

{{JSCode|1=someFunction(5, 400, 5000); // this is a call to a function, sending 3 parameters to it. a parameter is an input value for a function}} 

{{JSCode|1=// this is a function definition, which is a portion of code, don't forget the closing curly bracket to end the function definition
function someFunction() {
} }} 

{{JSCode|1=// this is a function definition, which takes 3 parameters. parameters are also called arguments
function someFunction(arg1, arg2, arg3) {
} }} 

{{JSCode|1=// this is a function without a name, also known as a lambda function
function() {}; }} 

{{JSCode|1=// this is a function which adds 2 numbers
// the word return is used to set the output of the function, as well as to stop the function running at the expression after the word return
// the result of add(..) is stored inside a variable named result
function add(a, b) {
return a + b;
}
var result = add(40, 20);
}}

==Data Types==

'''string'''
{{JSCode|1='this is a string'
"this is a string"}} 

'''number'''
{{JSCode|1=20
40.0
99e5
-20
-40.0}} 

'''boolean'''
{{JSCode|1=true
false}} 

'''null'''
{{JSCode|1=null

someVariable = null; // set a variable to null, the variable still exists}} 

'''undefined'''
{{JSCode|1=delete someVariable; // delete a variable, the variable no longer exists, and evaluates to undefined}} 

'''object'''
{{JSCode|1={} // an empty literal object

{'aa':5, 'bb':10} // a object literal with 2 elements, element with key aa has value 5, and element with key bb has value 10

function SomeClass() {
}
var someObject = new SomeClass; // an object of class SomeClass
}} 

Data type '''symbol''' also exists.

==Intrinsic Data Types==

'''Array'''
{{JSCode|1=[20, 50, 80] // an array with 3 elements, keys are 0 1 and 2, values are 20 50 and 80, respectively.}} 

'''Function'''
{{JSCode|1=function() {} // an empty function with no name

function someFuncName() // an empty function with a name
{
}

someFuncName = function() // an empty function with a name
{
} }} 

Many other intrinsic data types exist, check section 6.1.7.4 of the [http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf JavaScript Manual].

==Operators==

'''Math Operators'''
{{JSCode|1=+ - * / % // these are some mathematical operators

5 * 4 // results in 20

5 * 4 + 2 // results in 22

5 * (4 + 2) // results in 30}} 

==Variables==

{{JSCode|1=var someVariableName = 'some string value'; // this creates a local variable and assigns it a string value

someGlobalVariable = 50; // this either creates a global variable, or updates a variable, and assigns it a number value}}

==Conditions==

{{JSCode|1=var someVariable = 500;

functipn print(text)
{
// code here
}

// if
if (someVariable < 1000) {
print('value is less than 1000');
}

// if and else
if (someVariable < 200)
print('value is less than 200');
else
print('value is 200 or more');

// if, else if and else
if (someVariable < 100)
print('value is less than 100');
else if (someVariable < 300)
print('value is less than 300');
else if (someVariable < 500)
print('value is less than 500');
else
print('value is 500 or more');
}}

==Loops==

{{JSCode|1=functipn print(text)
{
// code here
}

// integer loop
for (var i=0; i<20; i++) {
print(i);
}

// array loop
var someArray = [20,50,80];
for (var i in someArray) {
print(someArray[i]);
} }}

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Mex at 13:23, 14 August 2018