Angular 2 restrict input field
you need use a directive. In the directive add a hotListener about input and check if match with the regExpr indicated. I make a directive mask some time ago. The directive in the stackblitz, with the edvertisment that the code is provide "as is" without warranty of any kind.
@Directive({
selector: '[mask]'
})
export class MaskDirective {
@Input()
set mask(value) {
this.regExpr = new RegExp(value);
}
private _oldvalue: string = "";
private regExpr: any;
private control: NgControl;
constructor(injector: Injector) {
//this make sure that not error if not applied to a NgControl
try {
this.control = injector.get(NgControl)
}
catch (e) {
}
}
@HostListener('input', ['$event'])
change($event) {
let item = $event.target
let value = item.value;
let pos = item.selectionStart; //get the position of the cursor
let matchvalue = value;
let noMatch: boolean = (value && !(this.regExpr.test(matchvalue)));
if (noMatch) {
item.selectionStart = item.selectionEnd = pos - 1;
if (item.value.length < this._oldvalue.length && pos == 0)
pos = 2;
if (this.control)
this.control.control.setValue(this._oldvalue, { emit: false });
item.value = this._oldvalue;
item.selectionStart = item.selectionEnd = pos - 1; //recover the position
}
else
this._oldvalue = value;
}
}
Be carefull, when you write "mask" in a string (or in the html). e.g. for a number width two decimals is:
[mask]="'^[+-]?([1-9]\\d*|0)?(\\.\\d\{0,2\})?$'"
(the \ must be writed as \\, { as \{, } as \} ...)
you can use an HTML5 feature, regex input
with regex pattern validation:
<input type="text" name="weight" value="" pattern="^[1-9]\d{0,*}\.\d{2}$" />
you can also use this library, decorate your input with the key :
<input type="text" pattern="[0-9]+" ng-pattern-restrict />
the repo :github.com/AlphaGit/ng-pattern-restrict