code: function genWeexHandler (params, handlerCode) {
    var innerHandlerCode = handlerCode;
    var exps = params.filter(function (exp) { return simplePathRE.test(exp) && exp !== '$event'; });
    var bindings = exps.map(function (exp) { return ({ '@binding': exp }); });
    var args = exps.map(function (exp, i) {
      var key = "$_" + (i + 1);
      innerHandlerCode = innerHandlerCode.replace(exp, key);
      return key
    });
    args.push('$event');
    return '{\n' +
      "handler:function(" + (args.join(',')) + "){" + innerHandlerCode + "},\n" +
      "params:" + (JSON.stringify(bindings)) + "\n" +
      '}'
  }
docs: Generate handler code with binding params on Weex /* istanbul ignore next