javascript number pattern validation code example

Example 1: number pattern js

/^[\+\-]?\d*\.?\d+(?:[Ee][\+\-]?\d+)?$/

/* 
	matched values:
    -2.14e10
    +14E-20
    42.69
*/

Example 2: regex on input

<form>
 <label for="username">Username <i>(letters and numbers only, no  punctuation or special characters)</i></label><br>
 <input name="username" id="username" pattern="[A-Za-z0-9]+">
</form>