Angular - Lifecycle Hooks
Find the bug in this Angular component:
```typescript
export class DemoComponent implements OnInit {
ngOnInit() {
this.loadData();
}
loadData() {
console.log(this.data.length);
}
data: string[];
}
```
Find the bug in this Angular component: ```typescript export class DemoComponent implements OnInit { ngOnInit() { this.loadData(); } loadData() { console.log(this.data.length); } data: string[]; } ```
medium📝 Debug Q7 of 15
Step-by-Step Solution
Solution:
Step 1: Analyze property initialization
data is declared but not initialized, so it is undefined by default.Step 2: Check method call in ngOnInit
loadData tries to access data.length, but data is undefined, causing a runtime error.Final Answer:
data is undefined when loadData runs, causing an error -> Option CQuick Check:
Initialize properties before use to avoid errors [OK]
Quick Trick: Initialize arrays before accessing length [OK]
Common Mistakes:
- Assuming declared properties are auto-initialized
- Ignoring runtime errors from undefined values
Master "Lifecycle Hooks" in Angular
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