JavaScript/Glossary

We try to keep consistency within the Wikibook when using technical terms. Therefore here is a short glossary.

object	An object is an associative array with key-value pairs. The pairs are called properties. All data types are derived from object - with the exception of primitive data types.
property	A key-value pair that is part of an object. The key part is a string or a symbol, the value part is a value of any type.
dot notation	The syntax to identify a property of an object using a dot: myObject.propertyKey
bracket notation	The syntax to identify a property of an object using brackets: myObject["propertyKey"]
curly braces notation	The syntax to express an object 'literaly' using { }: const myObject = {age: 39}
function	A function is a block of code introduced by the keyword function, an optional name, open parenthesis, optional parameters, and closing parenthesis. functiongreeting(person){return"Hello "+person;}; The above function is a named function. If you omit the function name, we call it a anonymous function. In this case, there is an alternative syntax by using the arrow syntax =>. function(person){// no function namereturn"Hello "+person;};// 'arrow' syntax. Here is only the definition of the function.// It is not called, hence not running.(person)=>{return"Hello "+person;};// or:(person)=>{return"Hello "+person};// assign the definition to a variable to be able to call it.letx=(person)=>{return"Hello "+person};// ... and execute the anonymous function by calling the variable// that points to it: x(...)alert(x("Mike"));// interesting:alert(x);// execute an anonymous function directly((person)=>{alert("Hello "+person);})("Mike");
method	A method is a function stored as a key-value pair of an object. The key represents the method name, and the value the method body. A method can be defined and accessed with the following syntax: letperson={firstName:"Tarek",city:"Kairo",show:function(){returnthis.firstName+" lives in "+this.city;},};alert(person.show());
callback function	A function that is passed as an argument to another function.
console	Every browser contains a window where internal information is shown. It's called the console and normally not opened. In most browsers, you can open the console via the function key F12.
item	A single value in an array. Same as 'element'.
element	A single value in an array. Same as 'item'.
parameter	When defining a function, variables can be declared in its signature, e.g.,: function f(param1, param2). Those variables are called parameters.
argument	When calling a function, variables can be stated to be processed in the function, e.g.,: f(arg1, arg2). Those variables are called arguments. The arguments replace the parameters which were used during the function definition.