title: Can HTML attributes be bypassed?
body: <p>Suppose I have an <code>&lt;input&gt;</code> tag with a <code>pattern</code> attribute (for example, a <code>pattern</code> that matches some format of a phone number), and I don’t go through the standard HTML page in the browser to <code>post</code> that data (for example, through postman), would that data still be check against the regex pattern? In other words, can html attributes (like <code>pattern</code> or <code>require</code>) be bypassed?</p>
  
  <p>More generally, in terms of security, should server side scripts always check against all possible invalid data?</p>