Objects – Methods (keys, values, entries)
Name:
Date:
Class:
A
Quick Questions
Shade in the A or B circle for each question.
1. Does Object.keys() return an array of an object's keys?
2. Does Object.values() return an array of an object's values?
3. Does Object.entries() return an array of key-value pairs?
4. Is 'object' with a lowercase o valid for these methods?
5. Do these methods need an object passed as an argument?
B
Match the Pairs
Draw a line connecting each item on the left to its match on the right.
| Left column | Right column | |
|---|---|---|
| 1Object.keys(person) | AReturns an array of person's values | |
| 2Object.values(person) | BWrong - 'Object' must start with a capital O | |
| 3Returns an array pairing each key with its value | CReturns an array of person's keys | |
| 4Collects only the property names of an object | DObject.entries(person) | |
| 5console.log(object.keys(a)); | EWrong - 'keys' must start with a lowercase k | |
| 6console.log(Object.Keys(b)); | FObject.keys(car) |
C
Definitions
Object.keys()
D
Fill in the Blanks
Complete each line of code by filling in the missing parts.
1.
console.log(Object.____(person));
2.
console.log(Object.______(person));
3.
console.log(Object._______(person));
4.
let names = Object.____(car);
5.
let vals = Object.______(car);
E
Spot the Error
Shade in the letter of the line that contains an error.
Question 1
A
console.log(object.keys(a));
B
let a = {x: 1};
C
console.log(a);
Question 2
A
let b = {y: 2};
B
console.log(Object.Keys(b));
C
console.log(b);
Question 3
A
let c = {z: 3};
B
console.log(c);
C
console.log(Object.values(c));
Question 4
A
console.log(Object.Values(d));
B
let d = {a: 1};
C
console.log(d);
Question 5
A
let e = {b: 2};
B
console.log(Object.entries(e));
C
console.log(e);
Answer Key
Objects – Methods (keys, values, entries)
Section A: Quick Questions
Q1
B — Yes
Q2
B — Yes
Q3
A — Yes
Q4
A — No
Q5
A — Yes
Section B: Match the Pairs
Q1
Object.keys(person) → Returns an array of person's keys
Q2
Object.values(person) → Returns an array of person's values
Q3
Returns an array pairing each key with its value → Object.entries(person)
Q4
Collects only the property names of an object → Object.keys(car)
Q5
console.log(object.keys(a)); → Wrong - 'Object' must start with a capital O
Q6
console.log(Object.Keys(b)); → Wrong - 'keys' must start with a lowercase k
Section C: Definitions
Q1
Object.keys() — Returns an array containing all the keys of a given object.Section D: Fill in the Blanks
Q1
console.log(Object.keys(person));Q2
console.log(Object.values(person));Q3
console.log(Object.entries(person));Q4
let names = Object.keys(car);Q5
let vals = Object.values(car);Section E: Spot the Error
Q1
A — 'Object' must start with a capital O, not lowercase.
Q2
B — 'keys' must be lowercase - a capital K causes an error.
Q3
C — This line is actually correct - Object.values() works this way.
Q4
A — 'values' must be lowercase - a capital V causes an error.
Q5
B — This line is actually correct - Object.entries() works this way.