javascript declare array

In JavaScript, all but 5 of the original data types are objects, including functions.5 Types of raw data: Number Boolean String Null Undefined In this context, let's talk about JavaScript objects.1. Create objectsvar obj = {}; A way of creating an object, called the object Direct amount (object Literal) var obj = new Object (); Create an empty object, as with {}For more knowled

attributes: constructor, length, and prototype.---> Constructor, as its name implies, is a constructor, that is, what the object is composed of. In other words, it is the object type. See the following example.Var arr = new Array (3 );If (arr. constructor = Array){Document. write ("This is an Array ");}If (test. constructor = Boolean){Document. write ("This is a

){Document. write ("This is an Array ");}If (test. constructor = Boolean){Document. write ("This is a Boolean ");}If (test. constructor = Date){Document. write ("This is a Date ");}If (test. constructor = String){Document. write ("This is a String ");}The output above is: This is an Array---> Length, that is, the length of ArrayVar arr = new Array (3 );Document.

Array object (Array object) and javascriptarray in JavaScript 1. method for creating an Array object: ---> Var arr = [1, 2, 3]; // simple definition method Now you can know Arr [0] = 1; arr [1] = 2; arr [2] = 3; ---> new Array (); var arr = new

Array.prototypeThe standard method on an object is designed to be reused on other objects-even if it is not an object that inherits from an array. Therefore, passbook some class array object (Array-like Objects) in JavaScript. A typical example is the arguments object of the function, which is described in Item 22. The

This article describes how to add and delete elements to and from a JavaScript Array object. Examples of how to use pop, push, splice, and concat methods are summarized, for more information about how to add and delete elements to and from a JavaScript Array, see the examples in this article. Share it with you for your

Summary of adding and deleting elements to and from Array objects in JavaScript Array, javascriptarray This example summarizes how to add and delete elements to and from a JavaScript Array object. Share it with you for your reference. The specific analysis is as follows: Pop

beginning to the end if omitted) returns an array of deleted elements, returning an empty array without deleting var a = [1,2,3,4,5,6,7,8]; A.splice (4); // = = Returns [5,6,7,8];a is [1,2,3,4] (A.splice); // = = Returns [2,3];a is [1,4] A.splice (a); // = = return [4];a Yes [1]　　　　　　The first two parameters specify the array elements that need to be

example var arr = new Array (3); if (Arr.constructor==array) { document.write ("This was an Array"); } if (Test.constructor==boolean) { document.write ("This is a Boolean"); } if (test.constructor==date) { document.write ("This is a Date"); } if (test.constructor==string) { document.write ("This is a String"); The result of the above output is that

1. sparse arrayIt is easy to create a sparse array with a specified length:Copy codeThe Code is as follows:> Var a = new Array (3 );>[,]> A. length3> A [0]Undefined When you traverse it, you will find that it does not have elements. JavaScript will skip these gaps.Copy codeThe Code is as follows:> A. forEach (function (x, I) {console. log (I + "." + x )});> A. ma

How can I tell if a JavaScript variable is an array or a obiect? Answer: 1, if you just use typeof to check the variable, whether it is array or object, will return to ' objec '. One possible answer to this problem is to check that the variable is not object and check that the variable has a number length (the length may also be 0 when it is an empty

instance of the object "inherits" the action given to the object's prototype.For array objects, use the following example to illustrate the purpose of the prototype property.Adds a method to the array object that returns the value of the largest element in the array. To do this, declare a function, add it to array.pro

Next is a "JavaScript array array Basics", which details all the methods of array. The methods of all arrays are defined on Array.prototype, and the Array.prototype itself is an array. Array.concat () Shallow copies the current array