Min / Max Validator in Angular 2 Final

To apply min/max validation on a number you will need to create a Custom Validator

Validators class currently only have a few validators, namely

• required
• requiredTrue
• minlength
• maxlength
• pattern
• nullValidator
• compose
• composeAsync

Validator: Here is toned down version of my number Validator, you can improve it as you like

static number(prms = {}): ValidatorFn {
    return (control: FormControl): {[key: string]: any} => {
      if(isPresent(Validators.required(control))) {
        return null;
      }
      
      let val: number = control.value;

      if(isNaN(val) || /\D/.test(val.toString())) {
        
        return {"number": true};
      } else if(!isNaN(prms.min) && !isNaN(prms.max)) {
        
        return val < prms.min || val > prms.max ? {"number": true} : null;
      } else if(!isNaN(prms.min)) {
        
        return val < prms.min ? {"number": true} : null;
      } else if(!isNaN(prms.max)) {
        
        return val > prms.max ? {"number": true} : null;
      } else {
        
        return null;
      }
    };
  }

Usage:

// check for valid number
var numberControl = new FormControl("", [Validators.required, CustomValidators.number()])

// check for valid number and min value  
var numberControl = new FormControl("", CustomValidators.number({min: 0}))

// check for valid number and max value
var numberControl = new FormControl("", CustomValidators.number({max: 20}))

// check for valid number and value range ie: [0-20]
var numberControl = new FormControl("", CustomValidators.number({min: 0, max: 20}))

I found a library implementing a lot of custom validators - ng2-validation - that can be used with template-driven forms (attribute directives). Example:

<input type="number" [(ngModel)]="someNumber" name="someNumber" #field="ngModel" [range]="[10, 20]"/>
<p *ngIf="someNumber.errors?.range">Must be in range</p>