Method attr

src/node/node.js:226–241

(...args)

  }

  attr(...args) {
    if(args.length === 0) return this.attributes[attributes];
    if(args.length > 1) {
      let [key, value] = args;
      if(typeof value === 'function') {
        value = value(this.attr(key));
      }
      this.setAttribute(key, value);
      return this;
    }
    if(typeof args[0] === 'string') {
      return this.getAttribute(args[0]);
    }
    Object.assign(this.attributes, args[0]);
    return this;
  }

  cloneNode() {
    const cloned = new this.constructor();