Angular typescript convert string to number

Question

I want to convert a string number (an integer represented as a string. ex "12" ) to a number

Model Class

export class Person{
  FirstName :  string | undefined ;
  Telephone:  number | undefined ;

}

TS file

  console.log("Person" + JSON.stringify(this.person));

The JSON appears as

{
    "FirstName ": "hhhhh",
    "Telephone": "1478525",
}

The Telephone property is a number and I want it to appear as follows (without the ""_ :

{
    "FirstName ": "hhhhh",
    "Telephone": 1478525,
}

Approaches I took.

this.person.Telephone = parseInt(telephone);

Above didn't work, it shows the same number enclosed as a string. I also tried the following:

this.person.Telephone as number

both approaches didn't work. Can someone help me solve this ?

Error I get if I don't convert to a number:

"The JSON value could not be converted to System.Int32. Path: $.Telephone | LineNumber: 2 | BytePositionInLine: 18."

Yes. Dont convert telephone to a number. A telephone number is not a number, it should be represented by a string. A number is something numeric, if you are wanting to know is it a number or a string ask yourself if it would make sense to perform a numeric operation on it. Would you ever add a number to a telephone number or subtract from it or divide by it. What about numbers in countries that start with 0? Those would have a problem if you convert it to a number. In the Netherlands almost all mobile numbers start with 06. — Igor
– Igor, Commented Feb 4, 2021 at 19:48
I get an error if I don't convert. Please look at updated post for the error. I tried adding a number (as integer ) from postman when sending request to server and it works then. So I need to make it a pure Integer. — Illep
– Illep, Commented Feb 4, 2021 at 19:50
Ok @Igor Let's say it's not Telephone but, age. Because I have another property which also has the same issue. — Illep
– Illep, Commented Feb 4, 2021 at 19:51
In that case parseInt is the way to go when you want to convert a string to a number. If you want more help you need to create an minimal reproducible example because "Above didn't work, " is not descriptive enough as this.person.Telephone = parseInt(telephone); should work just fine. — Igor
– Igor, Commented Feb 4, 2021 at 19:53
just change your class definition for the telephone property to be a string not a number export class Person{ FirstName : string | undefined ; Telephone: string| undefined ; } — Nadhir Falta
– Nadhir Falta, Commented Feb 4, 2021 at 19:57

Srijon Chakraborty · Accepted Answer · 2021-02-04 19:58:15Z

4

I think you can try this =>

let stringToNumberData = "123";
let numberValue = Number(stringToNumberData);
console.log(numberValue);
//Returns 123

OR

if(!isNaN(Number(stringToNumberData ))){
  let numberValue = Number(stringToNumberData );
  console.log(numberValue);
} else{
    console.log('Not a Number');
}

answered Feb 4, 2021 at 19:58

Srijon Chakraborty

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Comments

zerocewl · Accepted Answer · 2021-02-04 20:00:04Z

2

Just use the standard javascript Number

this.person.Telephone = Number(telephone); 
console.log("Person" + JSON.stringify(this.person));

answered Feb 4, 2021 at 20:00

zerocewl

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Comments

Akif Hadziabdic · Accepted Answer · 2021-02-04 20:24:52Z

1

You can use unary operator +

export class Person{
  FirstName :  string | undefined;
  Telephone:  number | undefined;
}
let person = new Person();
person.FirstName = "Name";
person.Telephone = 12345;
console.log(person);
person.Telephone = +"12345";
console.log(person);

Output:

Person { FirstName: 'Name', Telephone: 12345 }
Person { FirstName: 'Name', Telephone: 12345 }

PS: Use string as the data type for phone numbers.

edited Feb 4, 2021 at 20:24

answered Feb 4, 2021 at 20:01

Akif Hadziabdic

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Comments

Srikar Phani Kumar M · Accepted Answer · 2021-02-05 01:12:47Z

1

If you want to get a number from a string, you can use this approach.



let person = {
name: "Some Name",
age: "45"
};

console.log('Person obj before modification ==>', person);

person.age = parseInt(person.age, 10);

console.log('Person object after modifying ==>', person);

answered Feb 5, 2021 at 1:12

Srikar Phani Kumar M

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Comments

kumarras · Accepted Answer · 2022-06-21 02:11:54Z

0

One scenario where the string to number conversion might be needed is while fetching the params from the activated route in Angular. The easiest way is to append a + operator at the beginning.

constructor(private serversService: ServersService, private actRoute: ActivatedRoute) { }



ngOnInit() {
    const id = +this.actRoute.snapshot.params['id'];//convert param string to number if needed
    this.server = this.serversService.getServer(id);
    this.actRoute.params.subscribe((params: Params) => {
      this.server = this.serversService.getServer(+params['id']);
    })
  }

answered Jun 21, 2022 at 2:11

kumarras

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Comments

Steph TwX · Accepted Answer · 2022-10-27 15:04:04Z

0

  ngOnInit(): void {
    const stringValue: string = '341';
    const numberValue: number = +stringValue;
    // numberValue === 341
  }

answered Oct 27, 2022 at 15:04

Steph TwX

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1 Comment

rjumatov Over a year ago

Please keep in mind that +"" evaluates to 0 whereas parseInt("") returns NaN.

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