Firefox和Vue.js未定义event.path

使用composePath（）并为IE使用polyfill：https ://gist.github.com/rockinghelvetica/00b9f7b5c97a16d3de75ba99192ff05c

包括以上文件或粘贴代码：

// Event.composedPath
(function(e, d, w) {
  if(!e.composedPath) {
    e.composedPath = function() {
      if (this.path) {
        return this.path;
      } 
    var target = this.target;

    this.path = [];
    while (target.parentNode !== null) {
      this.path.push(target);
      target = target.parentNode;
    }
    this.path.push(d, w);
    return this.path;
    }
  }
})(Event.prototype, document, window);

然后使用：

var path = event.path || (event.composedPath && event.composedPath());