Sets the readOnly attribute on the element, if the expression inside ngReadonly is truthy.
A special directive is necessary because we cannot use interpolation inside the readOnly
attribute. See the interpolation guide for more info.
<INPUT
  ng-readonly="expression">
...
</INPUT>
      | Param | Type | Details | 
|---|---|---|
| ngReadonly | expression | 
         If the expression is truthy, then special attribute "readonly" will be set on the element  | 
    
<label>Check me to make text readonly: <input type="checkbox" ng-model="checked"></label><br/>
<input type="text" ng-readonly="checked" value="I'm Angular" aria-label="Readonly field" />