Uncaught TypeError: Cannot read properties of undefined (reading 'map')

Question

<div>
Tags:{' '}
<div>
{tags.map((tag, i) => (
<span key={i}>{tag}</span>
))}
</div>
</div>

The above section is causing error.

Answer 1

Just now found out the solution : https://www.webtips.dev/solutions/fix-cannot-read-properties-of-undefined-reading-map

Simply insert ? as shown below:
{tags?. Map((tag, i) => (

And the error is resolved!

Answer 2

In order to fix the error, you need to make sure that the array is not undefined. In order to do this, the simplest way is to use optional chaining.

{posts?.map(post => <Card details={post} />)}
You can use optional chaining by introducing a question mark after the variable. You can also use a logical AND, or use an if check prior to rendering to prevent running into issues.