April 2025
Intermediate to advanced
422 pages
9h 33m
Portuguese (Portugal, Brazil)
Content preview from Livro de receitas do TypeScript
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Capítulo 3. O sistema de tipos
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No capítulo anterior, aprendeste sobre os blocos de construção básicos que te permitem tornar o teu código JavaScript mais expressivo. Mas se tiveres experiência em JavaScript, compreendes que os tipos e anotações fundamentais do Typescript cobrem apenas um pequeno conjunto da sua flexibilidade inerente.
O TypeScript é suposto tornar as intenções em JavaScript mais claras, e quer fazê-lo sem sacrificar esta flexibilidade, especialmente porque permitiu que os programadores criassem APIs fantásticas usadas e adoradas por milhões. Pensa no TypeScript mais como uma forma de formalizar o JavaScript, em vez de o restringir. Entra no sistema de tipos do TypeScript.
Neste capítulo, desenvolverás um modelo mental de como pensar sobre tipos. Aprenderá como definir conjuntos de valores de forma ampla ou restrita, conforme necessário, e como alterar seu escopo ao longo do fluxo de controle. Também aprenderás como aproveitar um sistema de tipos estruturais e quando quebrar as regras.
Este capítulo marca a linha entre os fundamentos do TypeScript e as técnicas avançadas de tipos. Mas quer sejas um programador experiente em TypeScript ou estejas apenas a começar, este modelo mental será a base para tudo o que está para vir.
3.1 Modelação de dados com tipos de união e intersecção
Problema
Tens um modelo de dados elaborado que queres descrever ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.