Do Not Declare Strings, Numbers, and Booleans as Objects! Mockest | JavaScript

1.

What is the correct way to create an empty object...

A). var obj = {}; B). var obj = (); C). var obj = []; D). var obj = <{}>;

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2.

How do you access a property called "name" from an...

A). person.name B). person['name'] C). person->name D). person::name

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3.

What happens if you access a non-existent property...

A). It returns undefined. B). It throws an error. C). It returns null. D). It returns true.

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4.

How do you add a new property "age" with value 25...

A). person.age = 25; B). person['age'] = 25; C). person.add('age', 25); D). person.push('age', 25);

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5.

How can you remove a property "email" from an obj...

A). delete user.email; B). user.remove('email'); C). user.email = null; D). user.pop('email');

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6.

What does Object.keys(obj) return?

A). An array of object keys. B). An array of object values. C). An array of object properties. D). An array of object methods.

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7.

How do you check if an object has a property "col...

A). 'color' in obj B). obj.hasProperty('color'); C). obj.contains('color'); D). obj.propertyExists('color');

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8.

How do you iterate over all properties of an obj...

A). for (var prop in person) B). forEach(prop in person) C). for (var prop of person) D). forEach(prop of person)

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9.

What is the output of console.log(obj.prop) if ob...

A). It prints undefined. B). It throws an error. C). It prints null. D). It prints true.

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10.

How do you define a method "sayHello" in an obj...

A). person.sayHello = function() {}; B). person.sayHello: function() {}; C). person.sayHello = () {}; D). person.sayHello = function {};

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Do Not Declare Strings, Numbers, and Booleans as Objects! Mocktest

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