How to test that a JavaScript object has only specific fields/properties

up vote
0
down vote

favorite

I have this function which tests that an object has certain fields

validateServerResponseStructure(res: any) {

    let isTypeCorrect: boolean = (

      res.result != undefined) && (res['additional-info'] != undefined

    );

    return isTypeCorrect;

  }

Is there a way to test that res has only result and additional-info properties and nothing else?

edited Nov 11 at 7:17

Roy Scheffers

2,11281625

asked Nov 11 at 6:56

Manu Chadha

2,61611235

You should have used in operator instead: eg: 'result' in res
– zerkms
Nov 11 at 7:09

add a comment |

up vote
0
down vote

favorite

I have this function which tests that an object has certain fields

validateServerResponseStructure(res: any) {

    let isTypeCorrect: boolean = (

      res.result != undefined) && (res['additional-info'] != undefined

    );

    return isTypeCorrect;

  }

Is there a way to test that res has only result and additional-info properties and nothing else?

edited Nov 11 at 7:17

Roy Scheffers

2,11281625

asked Nov 11 at 6:56

Manu Chadha

2,61611235

You should have used in operator instead: eg: 'result' in res
– zerkms
Nov 11 at 7:09

add a comment |

up vote
0
down vote

favorite

I have this function which tests that an object has certain fields

validateServerResponseStructure(res: any) {

    let isTypeCorrect: boolean = (

      res.result != undefined) && (res['additional-info'] != undefined

    );

    return isTypeCorrect;

  }

Is there a way to test that res has only result and additional-info properties and nothing else?

edited Nov 11 at 7:17

Roy Scheffers

2,11281625

asked Nov 11 at 6:56

Manu Chadha

2,61611235

I have this function which tests that an object has certain fields

validateServerResponseStructure(res: any) {

    let isTypeCorrect: boolean = (

      res.result != undefined) && (res['additional-info'] != undefined

    );

    return isTypeCorrect;

  }

Is there a way to test that res has only result and additional-info properties and nothing else?

javascript typescript

edited Nov 11 at 7:17

Roy Scheffers

2,11281625

asked Nov 11 at 6:56

Manu Chadha

2,61611235

edited Nov 11 at 7:17

Roy Scheffers

2,11281625

asked Nov 11 at 6:56

Manu Chadha

2,61611235

edited Nov 11 at 7:17

Roy Scheffers

2,11281625

edited Nov 11 at 7:17

Roy Scheffers

2,11281625

edited Nov 11 at 7:17

Roy Scheffers

2,11281625

asked Nov 11 at 6:56

Manu Chadha

2,61611235

asked Nov 11 at 6:56

Manu Chadha

2,61611235

asked Nov 11 at 6:56

Manu Chadha

2,61611235

You should have used in operator instead: eg: 'result' in res
– zerkms
Nov 11 at 7:09

add a comment |

You should have used in operator instead: eg: 'result' in res
– zerkms
Nov 11 at 7:09

You should have used in operator instead: eg: 'result' in res
– zerkms
Nov 11 at 7:09

add a comment |

1 Answer
1

active

oldest

votes

up vote
2
down vote

accepted

Just check that the length of its keys is exactly two. Also, probably best to use strict equality comparison, if you want to ensure that the properties are not undefined:

validateServerResponseStructure(res: any) {

  let isTypeCorrect: boolean = (

    res.result !== undefined

    && res['additional-info'] !== undefined

    && Object.keys(res).length === 2

  );

  return isTypeCorrect;

}

In the unusual case that you may have properties that contain the undefined value, and you want to permit such values, check the length of the keys, and that both result and additional-info are included in the keys:

const keys = Object.keys(res);

let isTypeCorrect: boolean = (

  ['result', 'additional-info'].every(key => keys.includes(key))

  && keys.length === 2

)

edited Nov 11 at 7:13

answered Nov 11 at 6:58

CertainPerformance

67.3k143353

You say " best to use strict equality", but you don't use it. You should use typeof res.result !== "undefined" && typeof res['additional-info'] !== "undefined"
– Tsahi Asher
Nov 11 at 7:08

res.result !== undefined does not check if a property exists, but only if its value is not undefined. { foo: undefined } --- here the .foo property would exist yet it's undefined.
– zerkms
Nov 11 at 7:08

@TsahiAsher "Strict equality" refers to using === and !== rather than == and !=. Pretty sure adding typeof only adds a bit of syntax noise
– CertainPerformance
Nov 11 at 7:17

@zerkms - I don't understand your comment.
– Manu Chadha
Nov 11 at 16:52

@ManuChadha you asked "How to test that a JavaScript object has only specific fields/properties " --- you don't check if an object has a particular property with !== undefined. Equality to undefined has nothing to do with property presence. To check if property presents you need to use in or Object.keys as in this answer
– zerkms
Nov 11 at 22:37

add a comment |

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1 Answer
1

active

oldest

votes

1 Answer
1

active

oldest

votes

up vote
2
down vote

accepted

Just check that the length of its keys is exactly two. Also, probably best to use strict equality comparison, if you want to ensure that the properties are not undefined:

validateServerResponseStructure(res: any) {

  let isTypeCorrect: boolean = (

    res.result !== undefined

    && res['additional-info'] !== undefined

    && Object.keys(res).length === 2

  );

  return isTypeCorrect;

}

const keys = Object.keys(res);

let isTypeCorrect: boolean = (

  ['result', 'additional-info'].every(key => keys.includes(key))

  && keys.length === 2

)

edited Nov 11 at 7:13

answered Nov 11 at 6:58

CertainPerformance

67.3k143353

You say " best to use strict equality", but you don't use it. You should use typeof res.result !== "undefined" && typeof res['additional-info'] !== "undefined"
– Tsahi Asher
Nov 11 at 7:08

res.result !== undefined does not check if a property exists, but only if its value is not undefined. { foo: undefined } --- here the .foo property would exist yet it's undefined.
– zerkms
Nov 11 at 7:08

@TsahiAsher "Strict equality" refers to using === and !== rather than == and !=. Pretty sure adding typeof only adds a bit of syntax noise
– CertainPerformance
Nov 11 at 7:17

@zerkms - I don't understand your comment.
– Manu Chadha
Nov 11 at 16:52

@ManuChadha you asked "How to test that a JavaScript object has only specific fields/properties " --- you don't check if an object has a particular property with !== undefined. Equality to undefined has nothing to do with property presence. To check if property presents you need to use in or Object.keys as in this answer
– zerkms
Nov 11 at 22:37

add a comment |

up vote
2
down vote

accepted

Just check that the length of its keys is exactly two. Also, probably best to use strict equality comparison, if you want to ensure that the properties are not undefined:

validateServerResponseStructure(res: any) {

  let isTypeCorrect: boolean = (

    res.result !== undefined

    && res['additional-info'] !== undefined

    && Object.keys(res).length === 2

  );

  return isTypeCorrect;

}

const keys = Object.keys(res);

let isTypeCorrect: boolean = (

  ['result', 'additional-info'].every(key => keys.includes(key))

  && keys.length === 2

)

edited Nov 11 at 7:13

answered Nov 11 at 6:58

CertainPerformance

67.3k143353

You say " best to use strict equality", but you don't use it. You should use typeof res.result !== "undefined" && typeof res['additional-info'] !== "undefined"
– Tsahi Asher
Nov 11 at 7:08

res.result !== undefined does not check if a property exists, but only if its value is not undefined. { foo: undefined } --- here the .foo property would exist yet it's undefined.
– zerkms
Nov 11 at 7:08

@TsahiAsher "Strict equality" refers to using === and !== rather than == and !=. Pretty sure adding typeof only adds a bit of syntax noise
– CertainPerformance
Nov 11 at 7:17

@zerkms - I don't understand your comment.
– Manu Chadha
Nov 11 at 16:52

@ManuChadha you asked "How to test that a JavaScript object has only specific fields/properties " --- you don't check if an object has a particular property with !== undefined. Equality to undefined has nothing to do with property presence. To check if property presents you need to use in or Object.keys as in this answer
– zerkms
Nov 11 at 22:37

add a comment |

up vote
2
down vote

accepted

Just check that the length of its keys is exactly two. Also, probably best to use strict equality comparison, if you want to ensure that the properties are not undefined:

validateServerResponseStructure(res: any) {

  let isTypeCorrect: boolean = (

    res.result !== undefined

    && res['additional-info'] !== undefined

    && Object.keys(res).length === 2

  );

  return isTypeCorrect;

}

const keys = Object.keys(res);

let isTypeCorrect: boolean = (

  ['result', 'additional-info'].every(key => keys.includes(key))

  && keys.length === 2

)

edited Nov 11 at 7:13

answered Nov 11 at 6:58

CertainPerformance

67.3k143353

Just check that the length of its keys is exactly two. Also, probably best to use strict equality comparison, if you want to ensure that the properties are not undefined:

validateServerResponseStructure(res: any) {

  let isTypeCorrect: boolean = (

    res.result !== undefined

    && res['additional-info'] !== undefined

    && Object.keys(res).length === 2

  );

  return isTypeCorrect;

}

const keys = Object.keys(res);

let isTypeCorrect: boolean = (

  ['result', 'additional-info'].every(key => keys.includes(key))

  && keys.length === 2

)

edited Nov 11 at 7:13

answered Nov 11 at 6:58

CertainPerformance

67.3k143353

edited Nov 11 at 7:13

answered Nov 11 at 6:58

CertainPerformance

67.3k143353

answered Nov 11 at 6:58

CertainPerformance

67.3k143353

answered Nov 11 at 6:58

CertainPerformance

67.3k143353

You say " best to use strict equality", but you don't use it. You should use typeof res.result !== "undefined" && typeof res['additional-info'] !== "undefined"
– Tsahi Asher
Nov 11 at 7:08

res.result !== undefined does not check if a property exists, but only if its value is not undefined. { foo: undefined } --- here the .foo property would exist yet it's undefined.
– zerkms
Nov 11 at 7:08

@TsahiAsher "Strict equality" refers to using === and !== rather than == and !=. Pretty sure adding typeof only adds a bit of syntax noise
– CertainPerformance
Nov 11 at 7:17

@zerkms - I don't understand your comment.
– Manu Chadha
Nov 11 at 16:52

@ManuChadha you asked "How to test that a JavaScript object has only specific fields/properties " --- you don't check if an object has a particular property with !== undefined. Equality to undefined has nothing to do with property presence. To check if property presents you need to use in or Object.keys as in this answer
– zerkms
Nov 11 at 22:37

add a comment |

You say " best to use strict equality", but you don't use it. You should use typeof res.result !== "undefined" && typeof res['additional-info'] !== "undefined"
– Tsahi Asher
Nov 11 at 7:08

res.result !== undefined does not check if a property exists, but only if its value is not undefined. { foo: undefined } --- here the .foo property would exist yet it's undefined.
– zerkms
Nov 11 at 7:08

@TsahiAsher "Strict equality" refers to using === and !== rather than == and !=. Pretty sure adding typeof only adds a bit of syntax noise
– CertainPerformance
Nov 11 at 7:17

@zerkms - I don't understand your comment.
– Manu Chadha
Nov 11 at 16:52

@ManuChadha you asked "How to test that a JavaScript object has only specific fields/properties " --- you don't check if an object has a particular property with !== undefined. Equality to undefined has nothing to do with property presence. To check if property presents you need to use in or Object.keys as in this answer
– zerkms
Nov 11 at 22:37

You say " best to use strict equality", but you don't use it. You should use typeof res.result !== "undefined" && typeof res['additional-info'] !== "undefined"
– Tsahi Asher
Nov 11 at 7:08

res.result !== undefined does not check if a property exists, but only if its value is not undefined. { foo: undefined } --- here the .foo property would exist yet it's undefined.
– zerkms
Nov 11 at 7:08

@TsahiAsher "Strict equality" refers to using === and !== rather than == and !=. Pretty sure adding typeof only adds a bit of syntax noise
– CertainPerformance
Nov 11 at 7:17

@zerkms - I don't understand your comment.
– Manu Chadha
Nov 11 at 16:52

@ManuChadha you asked "How to test that a JavaScript object has only specific fields/properties " --- you don't check if an object has a particular property with !== undefined. Equality to undefined has nothing to do with property presence. To check if property presents you need to use in or Object.keys as in this answer
– zerkms
Nov 11 at 22:37

add a comment |

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