Add points on click
This example shows how to add a point whenever *the user clicks* on the board. The function `getMouseCoords` extracts the click coordinates from the event object and returns a `JXG.Coords` object with the point's coordinates on the board. The for loop in the event listener is to check if there is already a point as we don't want to create a point in this case.
// Define the id of your board in BOARDID
const board = JXG.JSXGraph.initBoard(BOARDID, {
boundingbox: [-5, 5, 5, -5],
axis: true
});
var getMouseCoords = function(e, i) {
var pos = board.getMousePosition(e, i);
return new JXG.Coords(JXG.COORDS_BY_SCREEN, pos, board);
},
handleDown = function(e) {
var canCreate = true,
i, coords, el;
if (e[JXG.touchProperty]) {
// index of the finger that is used to extract the coordinates
i = 0;
}
coords = getMouseCoords(e, i);
for (el in board.objects) {
if (JXG.isPoint(board.objects[el]) && board.objects[el].hasPoint(coords.scrCoords[1], coords.scrCoords[2])) {
canCreate = false;
break;
}
}
if (canCreate) {
board.create('point', [coords.usrCoords[1], coords.usrCoords[2]]);
}
};
board.on('down', handleDown);
This example is licensed under a Creative Commons Attribution 4.0 International License.
Please note that you have to mention The Center of Mobile Learning with Digital Technology in the credits.