Docly Developers
Function Updated 17 Oct 2026

isNumber(value, [minValue], [maxValue])

Checks if the value is a number or numeric text. Text may use a comma as decimal separator and spaces as thousands separators ("1 234,5" is a number). null gives false, and note that true and false count as numbers (1 and 0). Alias: isNum.

See also isInteger isString assert

Parameters

valueobjectrequired

Value to validate.

minValuenumberoptional

Minimum value (inclusive), or null to skip.

maxValuenumberoptional

Maximum value (inclusive), or null to skip.

Returns

Returns true if value is a number (within the specified range).

Example

Normal JavaScript, running in the browser or on the Docly™ server.
let t = "test";

if (!docly.isNumber(t))
    write("'test' is not a number \n");

let n = 123;
if (docly.isNumber(n, 100, 200))
    write("123 is a number between 100 and 200\n");
    
if (!docly.isNumber(n, 1, 10))
    write("123 is NOT a number between 1 and 10");