Typescript error message TS2314: One type argument is required for the generic type 'Array<T>'

Question

Typescript error message TS2314: One type argument is required for the generic type 'Array<T>'

I recently started my journey in learning typescript and have written some basic code.

class Learning {

    subjects: Array[string];
    hoursPerDay: number;

    constructor(subj: Array[string], hrs: number) {
        this.subjects = subj;
        this.hoursPerDay = hrs;
    }

    displaySubjects():void{

        for(let i=0; i<this.subjects.length; i++){
            console.log(this.subjects[i]);
        }
    }
}
let topics=["Math", "Science", "History"];
let learning = new Learning(topics, 5);

learning.displaySubjects();

I am encountering an error whenever I use an array:

Error TS2314: Generic type 'Array' requires 1 type argument(s). What am I doing wrong?

typescript

Answer 1

Answer №1

It is important to define generic arrays correctly:

```
const arr = new Array<string>()
```
const arr = string[]

Answer 2

It is important to define generic arrays correctly:

```
const arr = new Array<string>()
```
const arr = string[]

Answer 3

Answer №2

It is suggested to use the T[] syntax instead of Array< T > syntax.

The TSlint rule "array-type": [true, "array"]:

To ensure compilation, change Array[string] to Array < string > in your code.

nameOfStudents: Array<string>;
noOfteachers: number

constructor(name: Array<string>, no: number) {
    this.nameOfStudents = name;
    this.noOfteachers = no;
}

A better practice would be like this:

class School {

    nameOfStudents: string[];
    noOfteachers: number;

    constructor(name: string[], no: number) {
        this.nameOfStudents = name;
        this.noOfteachers = no;
    }

    printName(): void {
        for (const studentName of this.nameOfStudents) {
            console.log(studentName);
        }
    }
}

I highly recommend installing tslint for your project as it helps maintain clean Typescript code.

EDIT 18/12/22: tslint is deprecated, use eslint instead

Answer 4

It is suggested to use the T[] syntax instead of Array< T > syntax.

The TSlint rule "array-type": [true, "array"]:

To ensure compilation, change Array[string] to Array < string > in your code.

nameOfStudents: Array<string>;
noOfteachers: number

constructor(name: Array<string>, no: number) {
    this.nameOfStudents = name;
    this.noOfteachers = no;
}

A better practice would be like this:

class School {

    nameOfStudents: string[];
    noOfteachers: number;

    constructor(name: string[], no: number) {
        this.nameOfStudents = name;
        this.noOfteachers = no;
    }

    printName(): void {
        for (const studentName of this.nameOfStudents) {
            console.log(studentName);
        }
    }
}

I highly recommend installing tslint for your project as it helps maintain clean Typescript code.

EDIT 18/12/22: tslint is deprecated, use eslint instead

Typescript error message TS2314: One type argument is required for the generic type 'Array<T>'

Answer №1

Answer №2

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