CODEWITHSUNDEEP
typescriptangular
AdrienTorris
AdrienTorris

Reputation: 9391

Typescript .length return undefined

This issue makes me crazy ...

I have this code : 

if (control.value==null||control.value == "" || control.value == " " || control.value.length != 5) {
     // do something
}

My problem : control.value.length always returns 'undefined'.

I try to use a string variable like this but the result is the same.

var curVal: string = control.value;
if (curVal==null||curVal== "" || curVal == " " || curVal != 5) {
     // do something
}

Where am I wrong ?

Edit: Precision : my control.value is not null or empty, I test with the value 59000

This code :

console.log(control.value + ' - ' + control.value.length);

log this : 59000 - undefined

EDIT 2 : Thank's you, it's solved. The problem was my control.value was a number and not a string.

Upvotes: 12

Views: 43020

Answers (4)

Vibin S R
Vibin S R

Reputation: 11

In Typescript:

     let a="hello";
     let length=a.toString().length;
     console.log(length);

Output: 5

Upvotes: 1

Sajeevan Vinayakavaseerakan
Sajeevan Vinayakavaseerakan

Reputation: 131

Try Like these

String(control.value).length != 5

OR

control.value.toString().length != 5

Upvotes: 4

getName
getName

Reputation: 733

Sometimes there is this bug on Angular, since version 5.0.0 I think, even when the variable is not a number, I've to convert it to a number to use the '.length' property like below :

if (control.value==null||control.value == "" || control.value == " " || +(control.value.length) != 5) {
 // do something

It may works, just by adding the sign '+' before your var.length like: +(var.length)

Upvotes: 0

Thierry Templier
Thierry Templier

Reputation: 202176

I think that the type of your input isn't string but number.

@Component({
  selector: 'my-app',
  template: `
    <div>
      <input type="number" [ngFormControl]="ctrl">
    </div>
  `
})
export class AppComponent {
  constructor() {
    this.ctrl = new Control();
    this.ctrl.valueChanges.subscribe((val) => {
      console.log(val.length);
    });
  }
}

In this case val.length returns undefined since numbers don't have a length attribute.

See this plunkr for more details: https://plnkr.co/edit/5yp5ms9XY5Z3TEE2qYIh?p=preview.

Upvotes: 7

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