in templates/ydotm/bootstrap3.js [894:902]
Modal.prototype.enforceFocus = function () {
$(document)
.off('focusin.bs.modal') // guard against infinite focus loop
.on('focusin.bs.modal', $.proxy(function (e) {
if (this.$element[0] !== e.target && !this.$element.has(e.target).length) {
this.$element.focus()
}
}, this))
}