Javascript Regular Expression for valid HTTP Status Codes

RegEx for HTTP Status Codes

//DEFINE REGEX - valid input range is 100 thru 599
var regEx = /^[1-5][0-9][0-9]$/

//TEST REGEX
regEx.test(99)
=>false

regEx.test(100)
=>true

regEx.test(200)
=>true

regEx.test(300)
=>true

regEx.test(400)
=>true

regEx.test(500)
=>true

regEx.test(599)
=>true

regEx.test(600)
=>false