bootstrap 3.3.7 bug tooltip关闭时报Uncaught TypeError: Cannot read property 'off' of null

使用bootstrap 3.3.7的tooltip时，当tooltip关闭时会抛出Uncaught TypeError: Cannot read property ‘off’ of null的错误。github上有说是3.3.7的bug，见Tooltip.destroy() is missing a null check for that.$element #21830。

解决方法：直接修改bootstrap.js源码。如下

第一处：修改1489-1497行以下位置

      var complete = function () {
        var prevHoverState = that.hoverState
//        that.$element.trigger('shown.bs.' + that.type)
        // fix the bug Uncaught TypeError: Cannot read property 'off' of null
        null != that.$element && that.$element.trigger('shown.bs.' + that.type)
        that.hoverState = null

        if (prevHoverState == 'out') that.leave(that)
      }

第二处：修改1733-1748行以下位置

  Tooltip.prototype.destroy = function () {
    var that = this
    clearTimeout(this.timeout)
    this.hide(function () {
      // that.$element.off('.' + that.type).removeData('bs.' + that.type)
      // fix the bug Uncaught TypeError: Cannot read property 'off' of null
      null != that.$element && that.$element.off('.' + that.type).removeData('bs.' + that.type)
      if (that.$tip) {
        that.$tip.detach()
      }
      that.$tip = null
      that.$arrow = null
      that.$viewport = null
      that.$element = null
    })
  }