javascript declaring, and inserting to a multi-dimensional array

Question

I now multi-dimensional array in javascript is a bit silly. But in my program I have to use it. I want to declare a dynamic 3 columns and m-rows array using javascript and then in a loop i need to insert some element to that array. finally i want to display that array.

 var x = new Array();
 for (var y=0; y<=counter; y++) {
 x[y] = new Array (3);
x[y][0]='a';
x[y][1]='b';
x[y][2]='c';
 }

your help is highly appreciated ...

• Fabrizio Calderan: plase provide some code... what have you tried?

Answer 1

arrays grow as needed and so there is no point in declaring the length of the array. what you started with is fine. http://books.google.ca/books?id=4RChxt67lvwC&pg=PA141&lpg=PA141&dq=JS+array+grow+as+needed?&source=bl&ots=tgY8BlGXm8&sig=_3jcH1LTmYi9QiXxn9pHROpbN1s&hl=en&sa=X&ei=7v60T_XwA4ThggfGuoEX&ved=0CEoQ6AEwAQ#v=onepage&q=JS%20array%20grow%20as%20needed%3F&f=false

http://www.codingforums.com/showthread.php?t=5198

just a heads up it will create an array that is 1 bigger then counter. this is b/c in your for loop you have y<=counter and y starting at 0. if you want the length to be counter change it to

 y<counter

in order to display the array you might want to consider a for nested loop.

JS

for(var i=0; i<x.length; i++)
 for (var j=0; j<3; j++)
 alert(x[i][j]);

where x is the reference to the array. if you want to print the entire array at once consider creating a string from the elements in the array and print that

function displayArray(x){
var stringArray='';
 for(var i=0; i<x.length; i++)
 for (var j=0; j<3; j++)
 stringArray+= x[i][j];
 alert(stringArray);

}

Answer 2

Something like this?

var x = [
 [
 [1, 2, 3],
 [4,5,6]
 ],
 [
 [7, 8, 9]
 ] 
];
alert(x[0][1][2]);

This is one reason why JavaScript's variable syntax isn't always what it's cracked up to be. Compare to Java:

String[][][] x = new String[5][5][5];

• Andreas: There are two errors included in this answer. First the TO wants a dynamic approach for declaring the array. Second the comparison with Java is absolutley useless

Answer 3

Something like this maybe?

var sDataArray=MultiDimensionalArray(7,2); 
alert(sDataArray[0][0]); 
function MultiDimensionalArray(iRows,iCols) 
{ 
var i; 
var j; 
 var a = new Array(iRows); 
 for (i=0; i < iRows; i++) 
 { 
 a[i] = new Array(iCols); 
 for (j=0; j < iCols; j++) 
 { 
 a[i][j] = ""; 
 } 
 } 
 return(a); 
}

Being dynamic in rows maybe you want a list of arrays? You can also do a method to add a line, and increase the array size.

Answer 4

try something like this..
var cols = 3;
var rows = 5;
createArray(cols,rows);
function createArray(cols,rows) {
 var newArray = [];
 for(i=0;i<cols;i++) {
 newArray[i] = [];
 for(j=0;j<rows;j++) { 
 newArray[i][j] = "["+i+"]"+"["+j+"]";
 }
 } 
 return newArray;
}