I want to store coordinates into an array in javascript, I am new to javascript and do not have an idea how to do it.
Any help would be appreciated.
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6 Answers
There are a number of ways to store x,y coordinates:
Option 1 (every other index in an array):
function storeCoordinate(x, y, array) {
array.push(x);
array.push(y);
}
var coords = [];
storeCoordinate(3, 5, coords);
storeCoordinate(19, 1000, coords);
storeCoordinate(-300, 4578, coords);
coords[0] == 3 // x value (even indexes)
coords[1] == 5 // y value (odd indexes)
// to loop through coordinate values
for (var i = 0; i < coords.length; i+=2) {
var x = coords[i];
var y = coords[i+1];
}
Option 2 (simple object in an array):
function storeCoordinate(xVal, yVal, array) {
array.push({x: xVal, y: yVal});
}
var coords = [];
storeCoordinate(3, 5, coords);
storeCoordinate(19, 1000, coords);
storeCoordinate(-300, 4578, coords);
coords[0].x == 3 // x value
coords[0].y == 5 // y value
// to loop through coordinate values
for (var i = 0; i < coords.length; i++) {
var x = coords[i].x;
var y = coords[i].y;
}
Well, let's say we make it simple, you want to store coördinates, so we have x and y:
function coordinate(x, y) {
this.x = x;
this.y = y;
}
This is how you create Objects in javascript, they act like functions. With this function you can create your coordinates. Then all you need to do is create an array:
var arr = new Array();
arr.push(new coordinate(10, 0));
arr.push(new coordinate(0, 11));
That's it basically
3 Comments
Sara
Thankks how to retrieve them back from array...like using a for loop.
Dorpsidioot
Simple, for loop! for (var = 0; i < arr.length; i++) { alert(arr[i].x); }
ashleedawg
Awesome, thanks! I used this along with the js
some() method, to only add unique points to my array like if(!arr.some(arr => arr.x+','+arr.y === x+','+y)){ arr.push(new coordinate(x, y)); } (Credit also to TechRepublic)The push method would do the job:
var arr = new Array();
arr.push({ x : x_coordinate, y : y_coordinate });
You can then access them by using
arr[0].x (gives the x coordinate)
and
arr[0].y (gives the y coordinate).
Hope it helps.
Comments
These answers are not usable if you're trying to store a grid/matrix that you wanted to access data point by x,y values later.
var coords = [];
for(y=0; y < rows; y++){
for(x=0;x<cols; x++){
if(typeof coords[x] == 'undefined']){
coords[x] = [];
}
coords[x][y] = someValue;
}
}
//accessible via coords[x][y] later
1 Comment
ashleedawg
I saw a way to store coordinates using a Set. By using a Set you can store unique coordinates which can come in handy at times.
let coords = new Set();
coords.add(x + "," + y)
Comments
//creates a new point coordinate(x,y) - in this case its coordinate (col,row)
function coord(myColumn, myRow) {
return { col: myColumn, row: myRow}
}
// creates an array of coord
var myCoords = [
coord(0, 0),
coord(0, -2), coord(+1, -1),
coord(+1, +1), coord(0, +2),
coord(-1, +1), coord(-1, -1),
]
// access by - add coords and return a new one
function add(coordStart, coordEnd) {
return coord(coordStart.col + coordEnd.col, coordStart.row + coordEnd.row)
}
// call function
let myNewCoord = add(myCoords[3], myCoords[0])
