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, 1 return WEB, , . const, thisthis // - Uncaught TypeError: Assignment to constant variable. 1 It will also assert on the name. // error TS2322: Type 'number | ""' is not assignable to type 'number'. 1 const, const // error TS7010: 'hello', which lacks return-type annotation. Built with Docusaurus. , call()push() // Make the mock return `true` for the first call. // { } return , // : this. , boolean check Why not register and get more from Qiita? , JavaScript, // The function was called with a certain `this` context: the `element` object. Copyright 2019-2020, Future Corporation. new , 2 1 1manual mock, forEach , , .mock .mock thisthis , , (continuation-passing) , , API axios API data , API ()jest.mock() axios , .get mockResolvedValue axios.get('/users.json') , , jest.fn mockImplementationOnce , mockImplementation, mockImplementationOnce, mockImplementationOnce () jest.fn, ( this)API.mockReturnThis() , You can optionally provide a name for your mock functions, which will be displayed instead of "jest.fn()" in the test error output. undefinedvariable => 11, [, ] // variablethis.object, // , http://maeharin.hatenablog.com/entry/20130313/javascript_scopechain, console.logvariableundefined, you can read useful information later efficiently. setter/getter, TypeScript, Java, TypeScriptthisthis, JavaScriptthisthis , JavaScriptPythonundefined Warning: -file- is being assigned a //# sourceMappingURL, but already has one, TypeError: invalid Array.prototype.sort argument, Warning: 08/09 is not a legal ECMA-262 octal constant, SyntaxError: invalid regular expression flag "x", TypeError: X.prototype.y called on incompatible type, ReferenceError: can't access lexical declaration 'X' before initialization, TypeError: can't assign to property "x" on "y": not an object, RangeError: x can't be converted to BigInt because it isn't an integer, TypeError: can't convert BigInt to number, TypeError: can't define property "x": "obj" is not extensible, TypeError: property "x" is non-configurable and can't be deleted, TypeError: can't redefine non-configurable property "x", SyntaxError: applying the 'delete' operator to an unqualified name is deprecated, ReferenceError: deprecated caller or arguments usage, Warning: expression closures are deprecated, SyntaxError: "0"-prefixed octal literals and octal escape seq. number number , // implicitly has an 'any' return type. var self = this;, JavaScriptthis

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JavaScriptthis. operator, SyntaxError: missing ) after argument list, RangeError: repeat count must be non-negative, TypeError: can't delete non-configurable array element, RangeError: argument is not a valid code point, Error: Permission denied to access property "x", SyntaxError: redeclaration of formal parameter "x", TypeError: Reduce of empty array with no initial value, SyntaxError: "x" is a reserved identifier, RangeError: repeat count must be less than infinity, Warning: unreachable code after return statement, SyntaxError: "use strict" not allowed in function with non-simple parameters, ReferenceError: assignment to undeclared variable "x", ReferenceError: reference to undefined property "x", SyntaxError: function statement requires a name. // Uncaught TypeError: Assignment to constant variable. Use //# instead, Warning: String.x is deprecated; use String.prototype.x instead, Warning: Date.prototype.toLocaleFormat is deprecated. Licensed under CC BY-SA 4.0 and MIT(partially). const = ()=>{;}; const , function(), *constvarlet()const, const = (, ,,,,)=>{} , `${}`shift+@, undefined phppython, WEB1200m1, JavaScriptforEach, find, map, AWSEC2python3.py & , JavaScript()const { } = obj, JavaScriptSet(new Set, add, delete, clear, had), JavaScriptif&&&| 2, JavaScript/, JavaScript = () => { return }, export defaultexport.js.vue(default), JavaScriptiflengtharray[0] == nullNGnull, JavaScript=undefinedNaN, JavaScriptstartsWith, endsWith, indexOf, lastIndexOf, search, test, JavaScript(), export defaultimport fromTypeError: Object() is not a function, [Vue warn]: Error in render, JavaScriptif||()||&&, JavaScriptconcat, JavaScriptfindIndex23, JavaScriptconsole.log, JavaScript21reduce & concat, JavaScripterror: Unexpected token , axiosVue.jsAPI, then, catch, finally, Pythonpandasto_excel, Pythonpippippip3, PythonTypeError: 'NoneType', Windowsnode.jsnpmnodist, Vueimport fromexport default.js&.vue, Python DataFramepandas, Pythoncsvpandas.read_csvWEB. apply()call()bind() 2019 const, + _(), const Copyright 2022 Facebook, Inc. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); , ASP15, WordPress20, , JavaScriptletconst. , varlet, , let , const By following users and tags, you can catch up information on technical fields that you are interested in as a whole, By "stocking" the articles you like, you can search right away. type, , , .mock , .

TypeScript, Visit Mozilla Corporations not-for-profit parent, the Mozilla Foundation.Portions of this content are 19982022 by individual mozilla.org contributors. call()arguments 2017varfunctionletconst, (Expression)(Statement) - KEN, , , undefined, JavaScript, TypeScriptreturn, 1JavaScriptTypeScript, TypeScript , // Type '""' is not assignable to type 'number'. varfunction , this bind() self undefined, func Enable JavaScript to view data. Parameter 'num' implicitly has an 'any' type. are deprecated, SyntaxError: Using //@ to indicate sourceURL pragmas is deprecated. // The first argument of the first call to the function was 0, // The first argument of the second call to the function was 1, // The return value of the first call to the function was 42, // The first arg of the first call to the function was 'first arg', // The second arg of the first call to the function was 'second arg', // The return value of the first call to the function was 'return value'. // or you could use the following depending on your use case: // axios.get.mockImplementation(() => Promise.resolve(resp)), //Mock the default export and named export 'foo', // this happens automatically with automocking, // > 'first call', 'second call', 'default', 'default', // The mock function was called at least once, // The mock function was called at least once with the specified args, // The last call to the mock function was called with the specified args, // All calls and the name of the mock is written as a snapshot, // The first arg of the last call to the mock function was `42`, // (note that there is no sugar helper for this specific of an assertion).