{"record":{"id":"08466ce78ccdcc07","repo":"grafana/k6","slug":"last-argument-to-ws-connect-must-be-a-function","errorCode":null,"errorMessage":"last argument to ws.connect must be a function","messagePattern":"last argument to ws\\.connect must be a function","errorType":"validation","errorClass":null,"httpStatus":null,"severity":"error","filePath":"internal/js/modules/k6/ws/ws.go","lineNumber":640,"sourceCode":"}\n\nfunc parseConnectArgs(state *lib.State, rt *sobek.Runtime, args ...sobek.Value) (*wsConnectArgs, error) {\n\t// The params argument is optional\n\tvar callableV, paramsV sobek.Value\n\tswitch len(args) {\n\tcase 2:\n\t\tparamsV = args[0]\n\t\tcallableV = args[1]\n\tcase 1:\n\t\tparamsV = sobek.Undefined()\n\t\tcallableV = args[0]\n\tdefault:\n\t\treturn nil, errors.New(\"invalid number of arguments to ws.connect\")\n\t}\n\t// Get the callable (required)\n\tsetupFn, isFunc := sobek.AssertFunction(callableV)\n\tif !isFunc {\n\t\treturn nil, errors.New(\"last argument to ws.connect must be a function\")\n\t}\n\n\theaders := make(http.Header)\n\theaders.Set(\"User-Agent\", state.Options.UserAgent.String)\n\ttagsAndMeta := state.Tags.GetCurrentValues()\n\tparsedArgs := &wsConnectArgs{\n\t\tsetupFn:     setupFn,\n\t\theaders:     headers,\n\t\tcookieJar:   state.CookieJar,\n\t\ttagsAndMeta: &tagsAndMeta,\n\t}\n\n\tif common.IsNullish(paramsV) {\n\t\treturn parsedArgs, nil\n\t}\n\n\t// Parse the optional second argument (params)\n\tparams := paramsV.ToObject(rt)","sourceCodeStart":622,"sourceCodeEnd":658,"githubUrl":"https://github.com/grafana/k6/blob/93accf6570dcd306ca5e99cc44c393ee3797761b/internal/js/modules/k6/ws/ws.go#L622-L658","documentation":"Error \"last argument to ws.connect must be a function\" thrown in grafana/k6.","triggerScenarios":"Thrown at internal/js/modules/k6/ws/ws.go:640 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":[],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"93accf6570dcd306ca5e99cc44c393ee3797761b","analyzedAt":"2026-08-15T21:23:27.118Z","schemaVersion":2},"datasetVersion":"2026-08-15T22:17:37.221Z"}