Which is the difference between declaring a field as Array<any> and Array<Object>.
Is there some extra collection tools in typescript?
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3 Answers
An Object in TypeScript is the same thing as in JavaScript.
The difference is that any accepts primitives as well: a number is not an object, unless boxed to a Number.
So while an Array<any> can contain primitives, an Array<Object> can't.
TL;DR: don't use Object.
Source: TypeScript's Do's and Don'ts
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You are basically asking what's the difference between any and Object and that's answered in the docs about any:
The any type is a powerful way to work with existing JavaScript, allowing you to gradually opt-in and opt-out of type-checking during compilation. You might expect Object to play a similar role, as it does in other languages. But variables of type Object only allow you to assign any value to them - you can’t call arbitrary methods on them, even ones that actually exist:
let notSure: any = 4;
notSure.ifItExists(); // okay, ifItExists might exist at runtime
notSure.toFixed(); // okay, toFixed exists (but the compiler doesn't check)
let prettySure: Object = 4;
prettySure.toFixed(); // Error: Property 'toFixed' doesn't exist on type 'Object'.
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Object is the root type for classes and therefore has no properties, except for the inherent properties defined on Object.prototype.
any is a dynamic type and will compile no matter what properties you access on it.
For example:
const a: Object = "Object"
a.length // ERROR
const b: any = "Any"
b.length // Compiles
1 Comment
Shai
Well actually Object does have its inherent properties... I understand what you meant but it might be confusing for some.