Possible Duplicate:
Most efficient way to create a zero filled JavaScript array?
I wish to create an array in JS, the array will store integer value.
I would like to increment some of the values by 1, o at first I would like that each cell in the array would contain 0
Is it possible to do it in JS ?
Note: The array is of unknown size upon creation
var arr = [0,0,0,0];
incrementIndex(1,0);
incrementIndex(2,1);
function incrementIndex(index, value)
{
arr[ index ] = arr[ index ] + value;
}
Edit:
var arr = returnArray(10);
function returnArray(numberofIndexes)
{
var arr = new Array();
for ( var counter = 0; counter < numberOfIndexes; counter++)
{
arr.push(0);
}
return arr;
}
Array.prototype.increaseAt = function(index){
this[index] = this[index]+1 || 1
};
Array.prototype.getValueAt = function(index){
return this[index] || 0;
};
Use it like:
var testArray = [];
testArray.increaseAt(3);
console.log(testArray.getValueAt(3)); // 1
console.log(testArray.getValueAt(1)); // 0
You can access item of array by index of this item, like this item[index] += 1
