javascript - Multiple Regex validation for single value - alphanumeric with allowed special characters issue

Below is my regex for validating input name -starts with alphanumeric,allowed special characters.
It accepts "sample#@#@invalid" where am validating only allowed ()[].-_& characters.
where am doing wrong any help?

if(!/[A-Za-z0-9\s\)\(\]\[\._&-]+$/.test(inputText)){
 alert('Field name should be alphanumeric and allowed special characters _ . - [ ] ( ) &');
       }
if(!/^[A-Za-z0-9]/.test(inputText)){
      alert('Field name must start with an alphanumeric');
 }

Answer

Instead of negating the test, use a regular expression that inverts the character class:

if(/[^A-Za-z0-9\s)(\][._&-]/.test(inputText)){

Since this isn't anchored, it will match any character outside the allowed set anywhere in the input text.

function validate() {
    var inputText = document.getElementById("inputText").value;
    if (/[^A-Za-z0-9\s)(\][._&-]/.test(inputText)) {
        alert('Field name should be alphanumeric and alllowed  special characters _ . - [ ] ( ) &');
    }
    if (/^[^A-Za-z0-9]/.test(inputText)) {
        alert('Field name must start with an alphanumeric');
    }
}

DEMO