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27 lines
552 B
Markdown
27 lines
552 B
Markdown
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---
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id: b6fa7fa7-644f-42ab-bee6-71f4f58a60f2
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title: TypeScript Classes
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---
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# TypeScript 4.0
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## Class Property Inference from Constructors
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TypeScript 4.0 can now use control flow analysis to determine the types
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of properties in [classes](20201008090316-class_notation) when
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noImplicitAny is enabled.
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``` typescript
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class Square {
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// Previously: implicit any!
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// Now: inferred to `number`!
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area;
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sideLength;
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constructor(sideLength: number) {
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this.sideLength = sideLength;
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this.area = sideLength ** 2;
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}
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}
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```
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