JavaScript Numbers JavaScript has only one type of number. Numbers can be written with, or without, decimals: Example var x = 3.14; // A number with decimals var y = 34; // A number without decimals Extra large or extra small numbers can be written with scientific (exponent) notation: Example var x = 123e5; // 12300000 var y = 123e-5; // 0.00123 For a tutorial about JavaScript […]
Method Reuse With the call() method, you can write a method that can be used on different objects. All Functions are Methods In JavaScript all functions are object methods. If a function is not a method of a JavaScript object, it is a function of the global object (see previous chapter). The example below creates an […]
The code inside a JavaScript function will execute when “something” invokes it. Invoking a JavaScript Function The code inside a function is not executed when the function is defined. The code inside a function is executed when the function is invoked. It is common to use the term “call a function” instead of “invoke a function“. It […]
JavaScript functions are defined with the function keyword. You can use a function declaration or a function expression. Function Declarations Earlier in this tutorial, you learned that functions are declared with the following syntax: function functionName(parameters) { code to be executed } Declared functions are not executed immediately. They are “saved for later use”, and will be executed later, when they are invoked (called upon). […]
Date Object The Date object is used to work with dates and times. Date objects are created with new Date(). There are four ways of instantiating a date: var d = new Date(); var d = new Date(milliseconds); var d = new Date(dateString); var d = new Date(year, month, day, hours, minutes, seconds, milliseconds); For a tutorial about date and times, read our JavaScript Date Tutorial. Date Object Properties Property Description constructor Returns the function […]
A JavaScript function does not perform any checking on parameter values (arguments). Function Parameters and Arguments Earlier in this tutorial, you learned that functions can have parameters: functionName(parameter1, parameter2, parameter3) { code to be executed } Function parameters are the names listed in the function definition. Function arguments are the real values passed to (and received by) the function. Parameter Rules JavaScript function definitions […]
Scope determines the accessibility (visibility) of variables. JavaScript Function Scope In JavaScript there are two types of scope: Local scope Global scope JavaScript has function scope: Each function creates a new scope. Scope determines the accessibility (visibility) of these variables. Variables defined inside a function are not accessible (visible) from outside the function. Local JavaScript […]
A JavaScript function is a block of code designed to perform a particular task. A JavaScript function is executed when “something” invokes it (calls it). Example function myFunction(p1, p2) { return p1 * p2; // The function returns the product of p1 and p2 } Try it Yourself » JavaScript Function Syntax A JavaScript function is defined […]
