freeCodeCamp/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/testing-objects-for-properties.md

id, title, challengeType, forumTopicId, dashedName

id	title	challengeType	forumTopicId	dashedName
567af2437cbaa8c51670a16c	测试对象的属性	1	18324	testing-objects-for-properties

--description--

To check if a property on a given object exists or not, you can use the .hasOwnProperty() method. someObject.hasOwnProperty(someProperty) returns true or false depending on if the property is found on the object or not.

示例

function checkForProperty(object, property) {
  return object.hasOwnProperty(property);
}

checkForProperty({ top: 'hat', bottom: 'pants' }, 'top'); // true
checkForProperty({ top: 'hat', bottom: 'pants' }, 'middle'); // false

The first checkForProperty function call returns true, while the second returns false.

--instructions--

Modify the function checkObj to test if the object passed to the function parameter obj contains the specific property passed to the function parameter checkProp. If the property passed to checkProp is found on obj, return that property's value. If not, return Not Found.

--hints--

checkObj({gift: "pony", pet: "kitten", bed: "sleigh"}, "gift") 应该返回字符串 pony。

assert(
  checkObj({ gift: 'pony', pet: 'kitten', bed: 'sleigh' }, 'gift') === 'pony'
);

checkObj({gift: "pony", pet: "kitten", bed: "sleigh"}, "pet") 应该返回字符串 kitten。

assert(
  checkObj({ gift: 'pony', pet: 'kitten', bed: 'sleigh' }, 'pet') === 'kitten'
);

checkObj({gift: "pony", pet: "kitten", bed: "sleigh"}, "house") 应该返回字符串 Not Found。

assert(
  checkObj({ gift: 'pony', pet: 'kitten', bed: 'sleigh' }, 'house') ===
    'Not Found'
);

checkObj({city: "Seattle"}, "city") 应该返回字符串 Seattle。

assert(checkObj({ city: 'Seattle' }, 'city') === 'Seattle');

checkObj({city: "Seattle"}, "district") 应该返回字符串 Not Found。

assert(checkObj({ city: 'Seattle' }, 'district') === 'Not Found');

checkObj({pet: "kitten", bed: "sleigh"}, "gift") 应该返回字符串 Not Found。

assert(checkObj({ pet: 'kitten', bed: 'sleigh' }, 'gift') === 'Not Found');

--seed--

--seed-contents--

function checkObj(obj, checkProp) {
  // Only change code below this line
  return "Change Me!";
  // Only change code above this line
}

--solutions--

function checkObj(obj, checkProp) {
  if(obj.hasOwnProperty(checkProp)) {
    return obj[checkProp];
  } else {
    return "Not Found";
  }
}