Function _hover

src/components/fx/hover.js:267–984

(gd, evt, subplot, noHoverEvent, eventTarget)

// The actual implementation is here:
function _hover(gd, evt, subplot, noHoverEvent, eventTarget) {
    if (!subplot) subplot = 'xy';

    if (typeof subplot === 'string') {
        // drop zindex from subplot id
        subplot = subplot.split(zindexSeparator)[0];
    }

    // if the user passed in an array of subplots,
    // use those instead of finding overlayed plots
    var subplots = Array.isArray(subplot) ? subplot : [subplot];

    var spId;

    var fullLayout = gd._fullLayout;
    var hoversubplots = fullLayout.hoversubplots;
    var plots = fullLayout._plots || [];
    var plotinfo = plots[subplot];
    var hasCartesian = fullLayout._has('cartesian');

    var hovermode = evt.hovermode || fullLayout.hovermode;
    var hovermodeHasX = (hovermode || '').charAt(0) === 'x';
    var hovermodeHasY = (hovermode || '').charAt(0) === 'y';

    var firstXaxis;
    var firstYaxis;

    if (hasCartesian && (hovermodeHasX || hovermodeHasY) && hoversubplots === 'axis') {
        var subplotsLength = subplots.length;
        for (var p = 0; p < subplotsLength; p++) {
            spId = subplots[p];
            if (plots[spId]) {
                // 'cartesian' case

                firstXaxis = Axes.getFromId(gd, spId, 'x');
                firstYaxis = Axes.getFromId(gd, spId, 'y');

                var subplotsWith = (hovermodeHasX ? firstXaxis : firstYaxis)._subplotsWith;

                if (subplotsWith && subplotsWith.length) {
                    for (var q = 0; q < subplotsWith.length; q++) {
                        pushUnique(subplots, subplotsWith[q]);
                    }
                }
            }
        }
    }

    // list of all overlaid subplots to look at
    if (plotinfo && hoversubplots !== 'single') {
        var overlayedSubplots = plotinfo.overlays.map(function (pi) {
            return pi.id;
        });

        subplots = subplots.concat(overlayedSubplots);
    }

    var len = subplots.length;