vis.js Get Y value in a 2dgraph

Question

I'm using vis.js to diplay some dataset like on a 2dgraph :

var data_lat=[
{x:'2016-02-05T07:58:49.257',y:48.66081132,group:0},
{x:'2016-02-05T07:58:51.257',y:48.66081132,group:0},
...

I have put a draggable cursor on that graph with

graph_lat.addCustomTime(time[0].t, '1');

and I would ike to display the curent value of y depending of the position of my cursor.

I've looked though vis.js doc but I didn't find anything

---

//EDIT TO ANSWER//

This is the function i created to get the y value BUT : only for array with only one group in it

function closest (time, arr) {
var mid, time_mid;
var lo = 0;
var hi = arr.length - 1;
var time_number=moment(time).format('x');
//console.log(time_number);
while (hi - lo > 1) {
    mid = Math.floor ((lo + hi) / 2);
    time_mid=moment(arr[mid].x).format('x');
    if (time_mid < time_number) {
        lo = mid;
    } else {
        hi = mid;
    }
}
if (time_number - moment(arr[lo].x).format('x') <= moment(arr[hi].x).format('x') - time_number) {
    return arr[lo].y;
}
return arr[hi].y;

}

and here the one for array with many group (like many y for one x value) like this array :

{x:'2016-02-05T07:58:49.257',y:0,group:8},
{x:'2016-02-05T07:58:49.257',y:0,group:9},
{x:'2016-02-05T07:58:49.257',y:0,group:10},
{x:'2016-02-05T07:58:49.257',y:0,group:11},
{x:'2016-02-05T07:58:51.257',y:9,group:8},
{x:'2016-02-05T07:58:51.257',y:6,group:9},
{x:'2016-02-05T07:58:51.257',y:0,group:10},
{x:'2016-02-05T07:58:51.257',y:15,group:11},
{x:'2016-02-05T07:58:53.257',y:9,group:8}

function closest_multi_group (time, arr, groupID) {
var mid, time_mid;
var lo = 0;
var hi = arr.length - 1;
var time_number=moment(time).format('x');
//console.log(time_number);
while (hi - lo > 1) {
    mid = Math.floor ((lo + hi) / 2);
    time_mid=moment(arr[mid].x).format('x');
    if (time_mid < time_number) {
        lo = mid;
    } else {
        hi = mid;
    }
}
console.log((time_number - moment(arr[lo].x).format('x'))+'<='+(moment(arr[hi].x).format('x') - time_number));
if (time_number - moment(arr[lo].x).format('x') <= moment(arr[hi].x).format('x') - time_number) {
    console.log(arr[lo]);

    if(arr[lo+1].group < arr[lo].group){
        while(arr[lo].group!=groupID){

            lo--;
            console.log('lo-- '+lo);
        }
    }
    else{
        while(arr[lo].group!=groupID){

            lo++;
            console.log('lo++ '+lo);
        }
    }
    return arr[lo].y;
}

if(arr[hi-1].group > arr[hi].group){
    console.log(arr[hi]);
    while(arr[hi].group!=groupID){

        hi++;
        console.log('hi++ '+hi);
    }
}
else{
    console.log(arr[hi]);
    while(arr[hi].group!=groupID){

        hi--;
        console.log('hi-- '+hi);
    }
}
return arr[hi].y;
}

Answer 1

The event timechange gives you the current time of the custom time bar when being dragged. That is your x. With this time, you can loop over your data_lat to find the data point closest to x and display the corresponding y value somewhere.