angularjs - ng-pattern allows space when regex should prohibit it -

ng-pattern allowing spaces following pattern , cannot understand why so.

ng-pattern="/^[a-za-z\d\-\_]+$/" 

i have tried without escaping - , _, , result same: classes ng-valid , ng-valid-pattern applied.

i trying allow a-z (both capital , lower case) , dash , underscore. pattern seems work i'd expect on regex101 quite confusing.

update: text field marked invalid after valid character typed after space, not when space first character: eg (not hardcoded this, "sometext" , "some text" typed text inputs):

<input> sometext</input> //ng-valid <input>some text</input> //ng-invalid 

still quite confused why be.

angular trims inputs automatically. can disable ng-trim="false"

<input type="text" ng-model="model" ng-trim="false" ng-pattern="/^[a-za-z\d\-\_]+$/"/> 

see https://docs.angularjs.org/api/ng/input/input%5btext%5d