Adding the symbols \+?\-? into the character class allows for the presence of +, -, or ? within the string.
If you want to permit a + or - at the beginning and end of the string, use
/^[-+]?\d+[-+]?$/
^^^^^ ^^^^^
The [-+]? matches either + or - occurring zero or one time (due to the ? quantifier).
Alternatively, if the signs are only allowed at the start OR only at the end, utilize
/^([-+]?\d+|\d+[-+]?)$/
Explanation of the pattern:
^ - denotes the start of the string( - Group initiation
[-+]? - represents 1 or 0 instances of - or +\d+ - signifies 1 or more digits| - or\d+ - indicates 1 or more digits[-+]? - stands for 1 or 0 occurrences of - or +
) - marks the conclusion of the group$ - specifies the end of the string.
Furthermore, it's recommended to employ RegExp#test for checking if a string adheres to a specific pattern rather than using String#match:
var NumberplusminusRegex =/^[-+]?\d+[-+]?/;
if (NumberplusminusRegex.test(charTyped)) { // Returns yes or no
function btnNumber(){
charTyped=document.getElementById('txtNumber').value;
var NumberplusminusRegex =/^[-+]?\d+[-+]?/; // REMINDER: Avoid using /g with RegExp.test()
if (NumberplusminusRegex.test(charTyped)) { // Check for match
alert('yeah');
return true;
}
else {
alert('whoa');
return false;
}
}
<button onclick="btnNumber()">Click me</button>
<input type='text' id='txtNumber'/>