Why does this lose context in class callbacks and two TypeScript fixes?
This tests runtime this binding. Explain that regular functions get this from the call site, so passing a method strips its object context. Fix with an arrow property or constructor bind. Red flag: var self = this or claiming TypeScript changes binding.
This tests the difference between runtime this binding and lexical scope in TypeScript. A strong answer explains that regular functions receive this from the call site, not the definition, so extracting a class method and passing it to addEventListener loses the instance reference. It then demonstrates two fixes: defining the method as an arrow function property to lexically capture this, or explicitly binding it in the constructor. A red flag is suggesting var self = this or claiming that TypeScript changes JavaScript binding rules.
Read the original → developer.mozilla.org
- #typescript
- #javascript
- #this-binding
- #callbacks
- #dom-events
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