How to declare array of specific type in javascript

Question

Is it possible in java script to explicitly declare array to be an array of int(or any other type)?

something like var arr: Array(int) would be nice...

No. Javascript is dynamically typed. You could look at something like [typescript](http://www.typescriptlang.org/) which can be statically typed and will compile to vanilla javascript (the type checking only happens at compile however). — Matt Burland, Apr 14 '14 at 13:27
What do you need that for? If you're looking into type safety, have a look at http://www.typescriptlang.org/ — Bergi, Apr 14 '14 at 13:28
[Typed arrays](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Typed_arrays) may be available, depending on the browsers you target. However, they cannot be of *any* type. — Frédéric Hamidi, Apr 14 '14 at 13:31

score 9 · Accepted Answer · edited May 16 '22 at 13:05

9

var StronglyTypedArray=function(){
    this.values=[];
    this.push=function(value){
    if(value===0||parseInt(value)>0) this.values.push(value);
    else return;//throw exception
   };
   this.get=function(index){
      return this.values[index]
   }
}

EDITS: use this as follows

var numbers=new StronglyTypedArray();
numbers.push(0);
numbers.push(2);
numbers.push(4);
numbers.push(6);
numbers.push(8);
alert(numbers.get(3)); //alerts 6

edited May 16 '22 at 13:05

Mahdi Bashirpour

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answered Apr 14 '14 at 13:35

Bellash

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This works when calling `push` to add a value to the dynamic array. What if you want to prevent assignment of the wrong type, however? Say, `numbers[0] = 0; numbers[1] = 2` to assign the first two, then throw an exception if someone tries to do `numbers[2]='hello'` for example? – Trashman Apr 05 '22 at 19:03

score 2 · Answer 2 · answered Jul 22 '18 at 16:45

2

Array of specific type in typescript

export class RegisterFormComponent 
{
     genders = new Array<GenderType>();

     loadGenders()
     {
        this.genders.push({name: "Male",isoCode: 1});
        this.genders.push({name: "FeMale",isoCode: 2});
     }

}

type GenderType = { name: string, isoCode: number };    // Specified format

answered Jul 22 '18 at 16:45

Rahul Uttarkar

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4

The question is about javascript – alfoks Dec 31 '20 at 14:53

score 0 · Answer 3 · answered Jun 30 '20 at 07:22

If simply you want to restrict user to push values as per first value entered you can use below code

var stronglyTypedArray =  function(type) {
this.values = [];
this.typeofValue;
this.push = function(value) {
   if(this.values.length === 0) {
     this.typeofValue = typeof value;
     this.pushValue(value);
     return;   
   }
    if(this.typeofValue === typeof value) {
       this.pushValue(value);
    } else {
        alert(`type of value should be ${this.typeofValue}`)
    }
}

this.pushValue = function(value) {
     this.values.push(value);
}

}

If you want to pass your own type, you can customize the above code a bit to this

var stronglyTypedArray =  function(type) {
this.values = [];
this.push = function(value) {
    if(type === typeof value) {
       this.pushValue(value);
    } else {
        alert(`type of value should be ${type}`)
    }
}

this.pushValue = function(value) {
     this.values.push(value);
}

}

How to declare array of specific type in javascript

3 Answers3