Usage Notes

Validate against a minimum of 3

const control = new FormControl(2, Validators.min(3));

console.log(control.errors); // {min: {min: 3, actual: 2}}

Usage Notes

Validate against a maximum of 15

const control = new FormControl(16, Validators.max(15));

console.log(control.errors); // {max: {max: 15, actual: 16}}

Usage Notes

Validate that the field is non-empty

const control = new FormControl('', Validators.required);

console.log(control.errors); // {required: true}

Usage Notes

Validate that the field value is true

const control = new FormControl('some value', Validators.requiredTrue);

console.log(control.errors); // {required: true}

Usage Notes

Validate that the field matches a valid email pattern

const control = new FormControl('bad@', Validators.email);

console.log(control.errors); // {email: true}

Usage Notes

Validate that the field has a minimum of 3 characters

const control = new FormControl('ng', Validators.minLength(3));

console.log(control.errors); // {minlength: {requiredLength: 3, actualLength: 2}}

<input minlength="5">

Usage Notes

Validate that the field has maximum of 5 characters

const control = new FormControl('Angular', Validators.maxLength(5));

console.log(control.errors); // {maxlength: {requiredLength: 5, actualLength: 7}}

<input maxlength="5">

Usage Notes

Validate that the field only contains letters or spaces

const control = new FormControl('1', Validators.pattern('[a-zA-Z ]*'));

console.log(control.errors); // {pattern: {requiredPattern: '^[a-zA-Z ]*$', actualValue: '1'}}

<input pattern="[a-zA-Z ]*">

Pattern matching with the global or sticky flag

RegExp objects created with the g or y flags that are passed into Validators.pattern can produce different results on the same input when validations are run consecutively. This is due to how the behavior of RegExp.prototype.test is specified in ECMA-262 (RegExp preserves the index of the last match when the global or sticky flag is used). Due to this behavior, it is recommended that when using Validators.pattern you do not pass in a RegExp object with either the global or sticky flag enabled.

// Not recommended (since the `g` flag is used)
const controlOne = new FormControl('1', Validators.pattern(/foo/g));

// Good
const controlTwo = new FormControl('1', Validators.pattern(/foo/));