Decimal number regular expression, where digit after decimal is optional

Use the following:

/^\d*\.?\d*$/

• ^ – Beginning of the line;
• \d* – 0 or more digits;
• \.? – An optional dot (escaped, because in regex, . is a special character);
• \d* – 0 or more digits (the decimal part);
• $ – End of the line.

This allows for .5 decimal rather than requiring the leading zero, such as 0.5