Javascript - Loading XML into Multidimensional array

Javascript - Loading XML into Multidimensional array - javascript

I have been creating a game in HTML5 and javascript and have came across a problem.
The game uses a tile system to load the map. Currently my map is saved within a multidimensional array and looks like this:
var map = [ [1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
[1, 3, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 2, 0, 4, 1],
[1, 0, 0, 0, 0, 0, 2, 0, 4, 1],
[1, 0, 0, 0, 0, 0, 2, 0, 4, 1],
[1, 0, 0, 0, 0, 0, 2, 0, 4, 1],
[1, 0, 0, 0, 0, 0, 2, 0, 4, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1]]
I would like to add move levels by using a XML file to update the array.
My XML file currently looks like this:
<TileMaps>
<Level level="1">
<map>[ [1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
[1, 3, 0, 0, 0, 0, 2, 4, 0, 1],
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1]]
</map>
</Level>
<Level level="2">
<map>[ [1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
[1, 3, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 2, 0, 4, 1],
[1, 0, 0, 0, 0, 0, 2, 0, 4, 1],
[1, 0, 0, 0, 0, 0, 2, 0, 4, 1],
[1, 0, 0, 0, 0, 0, 2, 0, 4, 1],
[1, 0, 0, 0, 0, 0, 2, 0, 4, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1]]
</map>
</Level>
</TileMaps>
If anyone could help me load level="1" into my map variable that would be great.
Thanks

Don't use xml, use json. Here's a link to what its about, http://www.json.org/.
While not entirely precise, its pretty safe to think of json as a subset of javascript.
For example:
{
"levels":[
[
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
[1, 3, 0, 0, 0, 0, 2, 4, 0, 1],
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1]
],
[
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
[1, 3, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 2, 0, 4, 1],
[1, 0, 0, 0, 0, 0, 2, 0, 4, 1],
[1, 0, 0, 0, 0, 0, 2, 0, 4, 1],
[1, 0, 0, 0, 0, 0, 2, 0, 4, 1],
[1, 0, 0, 0, 0, 0, 2, 0, 4, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1]
]
]
}
Use http://jsonlint.org to validate json.

For anyone who wanted to know i fixed this by using the following code:
req=new XMLHttpRequest();
req.open("GET","my.xml",false);
req.send();
xmlDoc = req.responseXML;
map = JSON.parse(xmlDoc.getElementsByTagName('map')[0].firstChild.nodeValue);

Related

Is there a way to convert mp4/wav files to a byte array in nativescript?

Working on trying to write mp4 and wav files to byte arrays, so that I am able to share them with other apps. Would appreciate any help. Thanks

If I assume if you're using python then its same as reading text_file or video_file.
Let's assume if your filename is test.ts then you can use below function.
def get_bytes_from_file(filename):
return open(filename, "rb").read()
get_bytes_from_file("test.ts")
You can also use scipy inbuild function scipy.io.wavfile.read and/or scipy.io.wavfile.write.Refer this.
If you have decimal value that you would like to convert to binary you can use the following:
In [3]: import numpy as np
...:
...: def bitfield(n):
...: """Convert integer into bitfield (as list)
...: From StackOverflow: http://stackoverflow.com/a/10322018/
...: """
...: return [int(digit) for digit in bin(n)[2:]]
...:
In [4]: p = 0x91
...: p = np.array(bitfield(p))
In [5]: p
Out[5]: array([1, 0, 0, 1, 0, 0, 0, 1])
If you want to convert string message to binary you can use this:
In [1]: import numpy as np
import codecs
In[2]: s = '44.6488N,63.5752W,20.5,2.25,125.6,11.5,6.8,T10.5,271.4,35.5,44.6491N,63.5755W'.encode('utf-8')
In[4]: s.hex()
Out[4]: '34342e363438384e2c36332e35373532572c32302e352c322e32352c3132352e362c31312e352c362e382c5431302e352c3237312e342c33352e352c34342e363439314e2c36332e3537353557'
In[10]: print(codecs.decode("34342e363438384e2c36332e35373532572c32302e352c322e32352c3132352e362c31312e352c362e382c5431302e352c3237312e342c33352e352c34342e363439314e2c36332e3537353557", "hex").decode('utf-8'))
Out[10]: 44.6488N,63.5752W,20.5,2.25,125.6,11.5,6.8,T10.5,271.4,35.5,44.6491N,63.5755W
In[11]: hex_string = "34342e363438384e2c36332e35373532572c32302e352c322e32352c3132352e362c31312e352c362e382c5431302e352c3237312e342c33352e352c34342e363439314e2c36332e3537353557"
for i in range(len(hex_string)//2):
print('{0}'.format(hex_string[i*2:i*2+2]), end=":")
Out[11]: 34:34:2e:36:34:38:38:4e:2c:36:33:2e:35:37:35:32:57:2c:32:30:2e:35:2c:32:2e:32:35:2c:31:32:35:2e:36:2c:31:31:2e:35:2c:36:2e:38:2c:54:31:30:2e:35:2c:32:37:31:2e:34:2c:33:35:2e:35:2c:34:34:2e:36:34:39:31:4e:2c:36:33:2e:35:37:35:35:57:
In[12]: p = '34342e363438384e2c36332e35373532572c32302e352c322e32352c3132352e362c31312e352c362e382c5431302e352c3237312e342c33352e352c34342e363439314e2c36332e3537353557'
p = int(p, 16)
p = np.array(bitfield(p))
p
Out[12] : array([1, 1, 0, 1, 0, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 1, 1, 0,
0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 0, 1, 1, 1, 0,
0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 1, 0, 0, 1, 1, 1, 0, 0, 0, 1, 0,
1, 1, 0, 0, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0,
1, 0, 1, 1, 1, 0, 0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1,
0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 1,
1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1, 1,
0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1, 0, 0, 0, 1, 1, 0, 1, 0, 1, 0, 0,
1, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0,
0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 1,
0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1, 1,
0, 1, 0, 1, 0, 0, 1, 0, 1, 1, 1, 0, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0,
1, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 1,
0, 0, 1, 0, 1, 1, 1, 0, 0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 1,
0, 0, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0, 0, 0, 1, 1,
1, 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0,
1, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1, 0,
0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0,
1, 0, 0, 0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 1, 0,
1, 1, 1, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0,
1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 1, 1, 0,
0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 1,
0, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 1, 1, 0, 0, 0, 1, 1,
0, 1, 1, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 1, 0, 0,
1, 1, 0, 0, 0, 1, 0, 1, 0, 0, 1, 1, 1, 0, 0, 0, 1, 0, 1, 1, 0, 0,
0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1,
1, 0, 0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1,
0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 1])

How to fill an 2D array with a 2D Smaller array in JavaScript

I apologize if this is not well explained. I am quite new to JavaScript.
I have a 2D arrayA that is 10x10 and a 2D arrayB that is 5x8. The smaller arrayB is populated with data and the larger arrayA is just populated with 0's by default.
How can i move the data from arrayB to arrayA while still leaving the leftover space of arrayA as 0's?
The end result must be that arrayA should contain all of the data in the same order as arrayB but with the leftover space still just containing 0's.

Assuming I understood the question correctly, you can loop over each value of arrayB and assign it at the same indexes in arrayA:
const arrayA = Array(10).fill(0).map(_ => Array(10).fill(0))
const arrayB = Array(5).fill(0).map(_ => Array(8).fill(1))
for (let y = 0; y < arrayB.length; y++) {
for (let x = 0; x < arrayB[y].length; x++) {
arrayA[y][x] = arrayB[y][x]
}
}
console.log(arrayA.map(v => v.join(', ')).join('\n'))
The console.log is just for readability, to understand how the matrix looks.

A simple Array.map() will do the job:
const arrA = [
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
];
const arrB = [
[0,1,2,3,4],
[0,1,2,3,4],
[0,1,2,3,4],
[0,1,2,3,4],
[0,1,2,3,4],
[0,1,2,3,4],
[0,1,2,3,4],
[0,1,2,3,4],
];
const B2A = () => arrA.map(
(val, index) => val.map(
(subVal, subIndex) => {
if(arrB[index] && arrB[index][subIndex]) return arrB[index][subIndex]
return subVal;
})
)
console.log(B2A());

Use Array.from and iterate, while iterate check if the value exists in filler array. If exists use that value otherwise same array value.
const fill = (arr1, arr2) =>
Array.from(arr1, (arr, row) =>
Array.from(arr, (value, col) => (arr2[row] && arr2[row][col]) || value)
);
const arrA = [
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
];
const arrB = [
[0, 1, 2, 3, 4],
[0, 1, 2, 3, 4],
[0, 1, 2, 3, 4],
[0, 1, 2, 3, 4],
[0, 1, 2, 3, 4],
[0, 1, 2, 3, 4],
[0, 1, 2, 3, 4],
[0, 1, 2, 3, 4]
];
console.log(JSON.stringify(fill(arrA, arrB)));

Displaying an 11x11 Matrix on a Canvas

I've been trying to create a canvas that displays an 11x11 matrix.
const canvas = document.getElementById('canvasGame');
const context = canvas.getContext('2d');
context.scale(10, 10);
context.fillstyle = '#000';
context.fillstyle(0,0, canvas.width, canvas.height);
const matrix = [
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
];
Depending on the number inside the matrix it will create a rectangle of a certain colour.
I've created a basic function that goes through every entry.
if = 0, white rectangle.
else, black rectangle.
function drawMatrix(matrix){
matrix.forEach((row, y) =>{
row.forEach((value, x) => {
if(value === 0) {
context.fillStyle = 'white';
context.fillRect(x, y, 1, 1);
}
else
{
context.fillStyle = 'black';
context.fillRect(x, y, 1, 1);
}
});
});
}
drawMatrix(matrix);
However when I load my html file with my .js file and my canvas set-up it doesnt load anything apart from the styling I've applied to my canvas.
Screenshot: What it loads.
My HTML, if that matters.
<html>
<head>
<title>Testing Grounds</title>
<style>
body {
background: #345;
color: #fff;
font-family: sans-serif;
font-size: 2em;
text-align: center;
}
canvas {
border: dashed .2em #fff;
height: 90vh;
}
</style>
</head>
<body>
<h1>Test Zone</h1>
<p>Using a canvas to display 11x11 matrix</p>
<canvas id="canvasGame" width="350" height="350"/>
<script src="app.js"></script>
</body>
</html>

Here is also another way...
const canvas1 = document.getElementById('canvas1');
const context1 = canvas1.getContext('2d');
const canvas2 = document.getElementById('canvas2');
const context2 = canvas2.getContext('2d');
//context.scale(canvas.height / 16, canvas.height / 16);
matrix = [
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1],
[1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1],
[1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1],
[1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1],
[1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1],
[1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1],
[1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1],
[1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
];
function drawMatrix(matrix) {
z = matrix.map((c) => c.map((c) => c == 0 ? [255, 255, 255, 255] : [0, 0, 0, 255]));
i = new ImageData(Uint8ClampedArray.from(z.flat(2)), 12)
context1.putImageData(i, 0, 0);
context2.scale(16, 16);
context2.webkitImageSmoothingEnabled = false;
context2.mozImageSmoothingEnabled = false;
context2.imageSmoothingEnabled = false;
context2.drawImage(canvas1, 0, 0);
}
drawMatrix(matrix);
<center><canvas hidden id="canvas1" width=12 height=12></canvas></center>
<center><canvas id="canvas2" width=192 height=192></canvas></center>

const canvas = document.getElementById('canvas');
const context = canvas.getContext('2d');
// every drawn pixel will be 16 times bigger
context.scale(canvas.height / 16, canvas.height / 16);
const matrix = [
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1],
[1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1],
[1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1],
[1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1],
[1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1],
[1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1],
[1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1],
[1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
];
function drawMatrix(matrix) {
// write all pixels cycling thru rows and columns
matrix.forEach((row, y) => {
row.forEach((value, x) => {
context.fillStyle = value && "black" || "white";
context.fillRect(x, y, 1, 1);
});
});
}
drawMatrix(matrix); // draw the matrix
<center><canvas id="canvas" width=192 height=192></canvas></center>

The rectangles you're creating are 1 by 1 pixel and always in the upper-left. You should calculate the width/height of the rectangle (width / 11, height / 11). Then translate the x and width using those values. Something like the following should work:
function drawMatrix(matrix){
var cellWidth = canvas.width / 11.0;
var cellHeight = vanvas.height / 11.0;
matrix.forEach((row, y) =>{
row.forEach((value, x) => {
context.fillStyle = cellColor(value);
context.fillRect(x * cellWidth, y * cellHeight, cellWidth, cellHeight);
});
});
}
function cellColor(val) {
if(value == 0)
{
return 'white';
}
return 'black';
}
drawMatrix(matrix);
This will calculate the width and height of the cell, loop through each element, and draw the rectangle with either white or black depending on the value.
You should also make sure that the drawMatrix function is called after the body is loaded.

Constant value changes regardless of being constant; also, changes to one row of 2D array propagate to others

I was trying to do the 6th day of AdventOfCode.com, when I stumbled upon an annoying problem, that I don't know the cause of. I
var input = ["turn on 7,6 through 9,6","turn on 1,3 through 6,9"];
var grid = 0;
function Create2Darray(dimension) {
var arr = [0];
var arr2 = [0];
for (i=0; i<dimension; i++) {
arr2[i] = 0;
}
for (k=0; k<dimension; k++) {
arr[k] = arr2;
}
return arr;
}
grid = Create2Darray(10);
const p = grid; // THIS IS WHAT IT IS ALL ABOUT
temp = grid[4];
temp[5] = 3;
grid[4] = temp;
p; // outputs [[0, 0, 0, 0, 0, 3, 0, 0, 0, 0], [0, 0, 0, 0, 0, 3, 0, 0, 0, 0], [0, 0, 0, 0, 0, 3, 0, 0, 0, 0], [0, 0, 0, 0, 0, 3, 0, 0, 0, 0], [0, 0, 0, 0, 0, 3, 0, 0, 0, 0], [0, 0, 0, 0, 0, 3, 0, 0, 0, 0], [0, 0, 0, 0, 0, 3, 0, 0, 0, 0], [0, 0, 0, 0, 0, 3, 0, 0, 0, 0], [0, 0, 0, 0, 0, 3, 0, 0, 0, 0], [0, 0, 0, 0, 0, 3, 0, 0, 0, 0]] to console.
// Although we said: const p = grid;
// And at that time, grid was equal to [[0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 3, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]]
Secondly
this:
temp = grid[4];
temp[5] = 3;
grid[4] = temp;
What I expected was this:
[[0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 3, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]]
but I got:
[[0, 0, 0, 0, 0, 3, 0, 0, 0, 0], [0, 0, 0, 0, 0, 3, 0, 0, 0, 0], [0, 0, 0, 0, 0, 3, 0, 0, 0, 0], [0, 0, 0, 0, 0, 3, 0, 0, 0, 0], [0, 0, 0, 0, 0, 3, 0, 0, 0, 0], [0, 0, 0, 0, 0, 3, 0, 0, 0, 0], [0, 0, 0, 0, 0, 3, 0, 0, 0, 0], [0, 0, 0, 0, 0, 3, 0, 0, 0, 0], [0, 0, 0, 0, 0, 3, 0, 0, 0, 0], [0, 0, 0, 0, 0, 3, 0, 0, 0, 0]]
What am I doing wrong?
so the core questions:
Why did CONSTANT p change?
Why did ALL the "sub-arrays" within the main arrays change while I only selected the 5th value in the 4th "sub-array"?

About reference/copy
Javascript works "by reference", not "by copy" like C++. This means that after:
var a = [1, 2, 3];
var b = [a, a];
b is an array containing two references to the same array a, not two copies of a. For example after
b[0][0] = 99;
also b[1][0] will be 99 because b[0] and b[1] are references to the very same object.
If you want to build a matrix you need to build each row separately... for example:
var grid = [];
for (var i=0; i<100; i++) {
grid.push(new Array(100));
}
// Now grid is a matrix of 100x100 undefined elements
About const
Declaring a const reference to an array doesn't prevent the array content from being modified, you're only prevented from reassigning grid to reference something else.

A quick way to create a copy of an array is to use slice(0), for example instead of
for (k=0; k<dimension; k++) {
arr[k] = arr2;
}
you could have
for (k=0; k<dimension; k++) {
arr[k] = arr2.slice(0);
}
and then the code works as expected: every row of 2D array has the same content but the rows can be modified independently. See also: What's the point of .slice(0) here?

Convert byte array to signed int64 in javascript

I know that there is no int64 data type in js. But i need to convert a byte array into a signed int64 to get same result comparing to BitConverter.ToInt64() method in .NET class library. There is an implementations of big integers in javascript (BigInt.js) which accept hex as input and gets a bigInt as output but result is not same as BitConverter.ToInt64() in BCL.
Example:
BitConverter.ToInt64() for '0x40e00a35661f92a2' will result in -6732283969128439744
I need a solution for doing this in java script, performance is not issue.
edit:
feed data in normal order into BigInt.js:
javascript: new BigInt('0x40e00a35661f92a2')// shows 4674747637673464482
feed data in reverse order into BigInt.js:
javascript: new BigInt('0xa2921f66350ae040')// shows 11714460104581111872
which neither matches the BitConverter.ToInt64() result:
C SHARP: BitConverter.ToInt64(new byte[] { 0x40, 0xe0, 0x0a, 0x35, 0x66, 0x1f, 0x92, 0xa2 }, 0); // shows -6732283969128439744

There is an implementation for converting hex string to Int64 (both signed and unsigned) here: LINK
That code returns right result:
javascript: new HexStringToInt64StringConverter(true).convert('a2921f66350ae040') // will return -6732283969128439744 same as BitConverter.ToInt64() in BCL
The functions from the link:
function HexStringToInt64StringConverter(signed) {
var hexCode = {
'0':"0000",
'1':"0001",
'2':"0010",
'3':"0011",
'4':"0100",
'5':"0101",
'6':"0110",
'7':"0111",
'8':"1000",
'9':"1001",
'a':"1010",
'b':"1011",
'c':"1100",
'd':"1101",
'e':"1110",
'f':"1111"
};
var preComputedLongMath = {
"20":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
"21":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2],
"22":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4],
"23":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8],
"24":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 6],
"25":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 2],
"26":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 4],
"27":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 8],
"28":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 5, 6],
"29":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 1, 2],
"210":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 2, 4],
"211":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 4, 8],
"212":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 9, 6],
"213":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 1, 9, 2],
"214":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 6, 3, 8, 4],
"215":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 2, 7, 6, 8],
"216":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 5, 5, 3, 6],
"217":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 3, 1, 0, 7, 2],
"218":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 6, 2, 1, 4, 4],
"219":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 2, 4, 2, 8, 8],
"220":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 4, 8, 5, 7, 6],
"221":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 9, 7, 1, 5, 2],
"222":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 1, 9, 4, 3, 0, 4],
"223":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 3, 8, 8, 6, 0, 8],
"224":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 6, 7, 7, 7, 2, 1, 6],
"225":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 3, 5, 5, 4, 4, 3, 2],
"226":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 7, 1, 0, 8, 8, 6, 4],
"227":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 3, 4, 2, 1, 7, 7, 2, 8],
"228":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 6, 8, 4, 3, 5, 4, 5, 6],
"229":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 3, 6, 8, 7, 0, 9, 1, 2],
"230":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 7, 3, 7, 4, 1, 8, 2, 4],
"231":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 1, 4, 7, 4, 8, 3, 6, 4, 8],
"232":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 2, 9, 4, 9, 6, 7, 2, 9, 6],
"233":[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 5, 8, 9, 9, 3, 4, 5, 9, 2],
"234":[0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 7, 1, 7, 9, 8, 6, 9, 1, 8, 4],
"235":[0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 4, 3, 5, 9, 7, 3, 8, 3, 6, 8],
"236":[0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 8, 7, 1, 9, 4, 7, 6, 7, 3, 6],
"237":[0, 0, 0, 0, 0, 0, 0, 0, 1, 3, 7, 4, 3, 8, 9, 5, 3, 4, 7, 2],
"238":[0, 0, 0, 0, 0, 0, 0, 0, 2, 7, 4, 8, 7, 7, 9, 0, 6, 9, 4, 4],
"239":[0, 0, 0, 0, 0, 0, 0, 0, 5, 4, 9, 7, 5, 5, 8, 1, 3, 8, 8, 8],
"240":[0, 0, 0, 0, 0, 0, 0, 1, 0, 9, 9, 5, 1, 1, 6, 2, 7, 7, 7, 6],
"241":[0, 0, 0, 0, 0, 0, 0, 2, 1, 9, 9, 0, 2, 3, 2, 5, 5, 5, 5, 2],
"242":[0, 0, 0, 0, 0, 0, 0, 4, 3, 9, 8, 0, 4, 6, 5, 1, 1, 1, 0, 4],
"243":[0, 0, 0, 0, 0, 0, 0, 8, 7, 9, 6, 0, 9, 3, 0, 2, 2, 2, 0, 8],
"244":[0, 0, 0, 0, 0, 0, 1, 7, 5, 9, 2, 1, 8, 6, 0, 4, 4, 4, 1, 6],
"245":[0, 0, 0, 0, 0, 0, 3, 5, 1, 8, 4, 3, 7, 2, 0, 8, 8, 8, 3, 2],
"246":[0, 0, 0, 0, 0, 0, 7, 0, 3, 6, 8, 7, 4, 4, 1, 7, 7, 6, 6, 4],
"247":[0, 0, 0, 0, 0, 1, 4, 0, 7, 3, 7, 4, 8, 8, 3, 5, 5, 3, 2, 8],
"248":[0, 0, 0, 0, 0, 2, 8, 1, 4, 7, 4, 9, 7, 6, 7, 1, 0, 6, 5, 6],
"249":[0, 0, 0, 0, 0, 5, 6, 2, 9, 4, 9, 9, 5, 3, 4, 2, 1, 3, 1, 2],
"250":[0, 0, 0, 0, 1, 1, 2, 5, 8, 9, 9, 9, 0, 6, 8, 4, 2, 6, 2, 4],
"251":[0, 0, 0, 0, 2, 2, 5, 1, 7, 9, 9, 8, 1, 3, 6, 8, 5, 2, 4, 8],
"252":[0, 0, 0, 0, 4, 5, 0, 3, 5, 9, 9, 6, 2, 7, 3, 7, 0, 4, 9, 6],
"253":[0, 0, 0, 0, 9, 0, 0, 7, 1, 9, 9, 2, 5, 4, 7, 4, 0, 9, 9, 2],
"254":[0, 0, 0, 1, 8, 0, 1, 4, 3, 9, 8, 5, 0, 9, 4, 8, 1, 9, 8, 4],
"255":[0, 0, 0, 3, 6, 0, 2, 8, 7, 9, 7, 0, 1, 8, 9, 6, 3, 9, 6, 8],
"256":[0, 0, 0, 7, 2, 0, 5, 7, 5, 9, 4, 0, 3, 7, 9, 2, 7, 9, 3, 6],
"257":[0, 0, 1, 4, 4, 1, 1, 5, 1, 8, 8, 0, 7, 5, 8, 5, 5, 8, 7, 2],
"258":[0, 0, 2, 8, 8, 2, 3, 0, 3, 7, 6, 1, 5, 1, 7, 1, 1, 7, 4, 4],
"259":[0, 0, 5, 7, 6, 4, 6, 0, 7, 5, 2, 3, 0, 3, 4, 2, 3, 4, 8, 8],
"260":[0, 1, 1, 5, 2, 9, 2, 1, 5, 0, 4, 6, 0, 6, 8, 4, 6, 9, 7, 6],
"261":[0, 2, 3, 0, 5, 8, 4, 3, 0, 0, 9, 2, 1, 3, 6, 9, 3, 9, 5, 2],
"262":[0, 4, 6, 1, 1, 6, 8, 6, 0, 1, 8, 4, 2, 7, 3, 8, 7, 9, 0, 4],
"263":[0, 9, 2, 2, 3, 3, 7, 2, 0, 3, 6, 8, 5, 4, 7, 7, 5, 8, 0, 8],
"264":[1, 8, 4, 4, 6, 7, 4, 4, 0, 7, 3, 7, 0, 9, 5, 5, 1, 6, 1, 6],
"265":[3, 6, 8, 9, 3, 4, 8, 8, 1, 4, 7, 4, 1, 9, 1, 0, 3, 2, 3, 2]
};
if (typeof(signed) != 'boolean') signed = false;
function toBinary(hex) {
hex = hex.toLowerCase();
var binary = "";
for (var i = 0; i < hex.length; i++) {
binary += hexCode[hex[i]];
}
return binary;
}
function to1nsComplement(binary) {
var compliment = "";
for (var i = 0; i < binary.length; i++) {
compliment += (binary.charAt(i) == "1" ? "0" : "1");
}
return compliment;
}
function arrayAdd(a, b) {
var carry = 0;
var number = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];
for (var i = 19; i >= 0; i--) {
number[i] = a[i] + b[i] + carry;
if (number[i].toString().length > 1) {
carry = parseInt(number[i].toString().substring(0, number[i].toString().length - 1), 10);
number[i] = parseInt(number[i].toString().substring(number[i].toString().length - 1), 10)
} else {
carry = 0;
}
}
return number;
}
function removeZeroPad(number) {
var lock = false;
var output = [];
for (var i = 0; i < number.length; i++) {
if (lock) {
output.push(number[i]);
} else {
if (number[i] != 0) {
lock = true;
output.push(number[i]);
}
}
}
return output;
}
function binaryToDec(binary) {
var negative = false;
if (signed && (binary.charAt(0) == 1)) {
negative = true;
}
if (signed) {
binary = binary.substring(1);
if (negative) {
binary = to1nsComplement(binary);
}
}
var pos = 0;
var number = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];
for (var i = binary.length - 1; i >= 0; i--) {
if (binary.charAt(i) == 1) {
number = arrayAdd(number, preComputedLongMath["2" + pos])
}
pos++;
}
if (negative) {
number = removeZeroPad(arrayAdd(number, preComputedLongMath["20"]));
number.splice(0, 0, "-");
} else {
number = removeZeroPad(number);
}
return number.join("");
}
this.convert = function (hex) {
var binary = toBinary(hex);
return binaryToDec(binary);
};
}

Develop Reference

JavaScript is the programming language of the Web.

Javascript - Loading XML into Multidimensional array - javascript

For anyone who wanted to know i fixed this by using the following code: req=new XMLHttpRequest(); req.open("GET","my.xml",false); req.send(); xmlDoc = req.responseXML; map = JSON.parse(xmlDoc.getElementsByTagName('map')[0].firstChild.nodeValue);

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Convert byte array to signed int64 in javascript

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