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SirJosh3917

Formerly ninjasupeatsninja

From: USA

Joined: 2015-04-05

Posts: 2,095

[Release] JSParse

JSParse is like InitParse, but for javascript.

Check out the clean version of it to check source code, or include it in your own projects using the compressed version.

If you do use it, please keep the header comments. I'm putting this code in the public domain, so if you wanna use it, you can, I don't really care.

NOTE: I drew some inspiration off of LukeM's BlockHandler.js ( PIOTypes )
and off of Processor's InitParse ( for making sure it won't break entirely ).

If you have a way to improve the code speed wise, or make it smaller, do tell of said ways. I'll update JSParse to include your code if you do.

▼Simple Usage Example

var map = [[[]]];
onMessage = function(message) {
	//TODO: uncomment triple line comments if you want to check if it works - also include a canvas somewhere on the page.
	///var ctx = document.querySelector("canvas").getContext("2d");
	///ctx.fillStyle = "rgba(0,0,0,255)";

	switch(message.type) {
		case "init": {
			var map = []; //init map

			for (var i = 0; i < 2; i++) {
				map.push([]);
				for (var j = 0; j < message.getInt(18); j++) {
					map[i].push([]);
					for (var k = 0; k < message.getInt(19); k++) {
						map[i][j].push([]);
					}
				}
			}

			jsparse(message).forEach((j) => {
				map[j.layer][j.x][j.y] = j;

				///ctx.fillRect( j.x, j.y, 1, 1);
			});
			//TODO: something with the data
		} break;
		case "reset": {
			jsparse(message).forEach((j) => {
				map[j.layer][j.x][j.y] = j;

				///ctx.fillRect( j.x, j.y, 1, 1);
			});
		} break;
	}
};

▼What jsparse(e) returns

An array of objects, similar to the following:
[
    {
        x: 0,
        y: 0,
        id: 9,
        layer: 0,
        args: []
    }
]

Pretty straight-forward to use IMO, but if you need help, I ( and hopefully other forumers ) will be there to provide it.

If you encounter any problems, please do let me know. I tried to do my best to be careful about releasing this, but I may have made mistakes.

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William L. Burnett

Member

Joined: 2018-03-17

Posts: 17

Re: [Release] JSParse

Thank you for sharing!

▼Lesson

These two lines in your code are used for the byte array positions.

x: (xPos[j] << 8) | xPos[j + 1],
y: (yPos[j] << 8) | yPos[j + 1] //no idea what this does but it works, thanks proc

Each standard byte in an array is one octect, or 8 bits. Each bit can be a 0 or a 1. The if all the bits in the octect (highest possible number) are 1, which equates to 11111111 and if you convert that to decimal it is 255. If each position could only be hold on a byte (or 8 bits), that would mean the largest possible integer (in this case world size) would be 255 x 255 worlds. If two bytes are used instead of 1, that is 2 octects or 1111111111111111 which converted to decimal is 65535, which is the largest possible world size at the moment.

So now we know that positions of blocks are stored in two bytes each.

What the code does above is a bitwise operator by shifting the first byte 8 bits to the left and OR-ing the second byte. If the first byte was 10001001 and the second was 11111111, it would first shift the first byte 8 bits to the left which produces this: 1000100100000000, and the OR-ing does whatever is a 1 in the place, you keep it in the new one which makes this: 1000100111111111.

I hope that helped explain those two lines of code that you wrote.

(I believe I didn't make any mistakes, but someone please comment if I did.)

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