Multiple typescript constructors

Question

I’m struggling with TS constructors. Ill post this on stackoverflow, also.

Say you want to make the equivalent of these three constructors:

public Animal(){ this.name = “default”; this.noise =””; public Animal(string name){ this.name = name; this.noise = “”; } public Animal(string name, string noise){ this.name = name; this.noise = noise; }

Do you do something like this in Typescript?

Constructor(name?:string, noise?:string){ if(name!= null) this.name =name; else this.name = ""; if(string != null) this.noise = noise; else this.noise = ""; }

And so forth?

What about if you also have various primitives coming in say, you could declare an animal with an int or a string. Do you just use instanceof?

Thanks! Nathan

Ryan Cavanaugh · Accepted Answer · 2014-05-19 18:43:45Z

This can be done very simply:

class Animal { public name: string; public noise: string; constructor(name = 'default', noise = '') { this.name = name; this.noise = noise; } }

This is also exactly equivalent to:

class Animal { constructor(public name = 'default', public noise = '') { } }

Note that missing parameters in JavaScript have the value undefined, not null.

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