Doubts about javascript [closed]

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Doubts about javascript [closed]

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#1 by (1 votes)

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I have some questions about Javascript.

What is the array that has the properties? I think I read that the creation is different between var array = []; that var array = new Array();

When you create an array of the form var array = new Array(); is it necessary to put some number in the parameters?

I remember learning to create an array with undefined elements, but I do not remember the commas very well, it was like var array = [,,,,,,]; I think here there would be 5 elements undefined

When we are in the same function and at the beginning of the function they place var algo; , then through the middle of the function they define it as algo = 2; and then at the end as algo = 4; , at the end what happens with The variable? the 2 will be replaced by the 4? , are they concatenated? what happens? , because if I do this with an array ( array[array.length] = "Elemento6"; ), in this case an element is added, but with the variables how are you going?

javascript

asked by Eduardo Sebastian 20.04.2017 в 12:10

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1 answer

tip Database? [closed] can you help me generate a TRIGGER in BD ORACLE?

score 1 · Accepted Answer

We are going through steps:

1-In principle there is no difference between writing var array=[] and var array= new Array() almost never, except in one case, which is when you fill in numbers. Example:

var numeros = [45];

This creates an array with the number 45 in the 0 position.

var numeros= new Array(45);

this creates you a matrix of 45 positions.

2- When you create a matrix in this way var array=new Array(); you can create it empty so you can go putting all the objects you want or you can create it with a fixed length, but this last one is not recommended because when you use the method .length of the matrix will never be 0 and this can give many problems when using it.

The other two questions I will not answer because I am not sure of its use and the last one could not answer it correctly since it depends on the practice of each user.