[Solved] What is wrong with this RouterLink usage?<a [routerLink]="['/product', productId]">Product</a>Assuming productId is undefined. | Angular

Angular - Routing

What is wrong with this RouterLink usage?

<a [routerLink]="['/product', productId]">Product</a>

Assuming productId is undefined.

AThe link will not render in the DOM.

BThe link will navigate to '/product/undefined', which is likely unintended.

CAngular will throw a runtime error and stop navigation.

DAngular will replace undefined with an empty string automatically.

Step-by-Step Solution

Solution:

Step 1: Understand undefined parameter in RouterLink
If a parameter is undefined, Angular converts it to the string 'undefined' in the URL.
Step 2: Analyze consequences
This results in a URL like '/product/undefined', which is usually not desired.
Final Answer:
The link will navigate to '/product/undefined', which is likely unintended. -> Option B
Quick Check:
Undefined param becomes 'undefined' string in URL [OK]

Quick Trick: Check variables passed to RouterLink for undefined [OK]

Common Mistakes:

MISTAKES

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What is wrong with this RouterLink usage?