Object keys and values in Javascript - Step-by-Step Execution

Concept Flow - Object keys and values

Start with an object

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Get keys using Object.keys(obj)

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Get values using Object.values(obj)

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Use keys and values as arrays

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End

We start with an object, then extract its keys and values as arrays to use them separately.

Execution Sample

Javascript

const obj = {a: 1, b: 2};
const keys = Object.keys(obj);
const values = Object.values(obj);
console.log(keys);
console.log(values);

This code gets the keys and values from an object and prints them.

Execution Table

Step	Action	Expression	Result
1	Create object	const obj = {a: 1, b: 2};	{a: 1, b: 2}
2	Get keys	Object.keys(obj)	['a', 'b']
3	Get values	Object.values(obj)	[1, 2]
4	Print keys	console.log(keys)	['a', 'b']
5	Print values	console.log(values)	[1, 2]

💡 All keys and values extracted and printed.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
obj	undefined	{a:1, b:2}	{a:1, b:2}	{a:1, b:2}	{a:1, b:2}
keys	undefined	undefined	['a', 'b']	['a', 'b']	['a', 'b']
values	undefined	undefined	undefined	[1, 2]	[1, 2]

Key Moments - 2 Insights

Why do Object.keys(obj) and Object.values(obj) return arrays?

Because keys and values are multiple items, JavaScript groups them into arrays for easy use, as shown in steps 2 and 3.

Are the keys and values always in the same order?

Yes, Object.keys and Object.values return arrays where the order of keys matches the order of values, so keys[i] corresponds to values[i]. See steps 2 and 3.

Visual Quiz - 3 Questions

Look at the execution table, what is the value of 'keys' after step 2?

A ['a', 'b']

B [1, 2]

C {a:1, b:2}

D undefined

💡 Hint

Check the 'Result' column for step 2 in the execution_table.

At which step do we get the array of values from the object?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Look for Object.values(obj) in the 'Expression' column.

If the object had a new key 'c: 3', how would the 'keys' array change after step 2?

A ['a', 'b']

B ['a', 'b', 'c']

C ['c', 'a', 'b']

D [1, 2, 3]

💡 Hint

Object.keys returns keys in insertion order, see variable_tracker for keys array.

Concept Snapshot

Object.keys(obj) returns an array of all keys in obj.
Object.values(obj) returns an array of all values in obj.
Keys and values arrays have matching order.
Use these to loop or access keys/values separately.
Example: keys = Object.keys(obj); values = Object.values(obj);

Full Transcript

We start with an object that has keys and values. Using Object.keys, we get an array of the keys. Using Object.values, we get an array of the values. Both arrays keep the same order so each key matches its value by position. We print these arrays to see the keys and values separately. This helps when you want to work with keys or values alone.