JS/ 천 단위마다 콤마(,) 자동 생성

HTML

 <input type="text" id="price" onkeyup="inputNumberFormat(this)"/>

onkeyup 속성은 현재 요소에서 onKeyUp 이벤트 핸들러를 반환합니다.
https://developer.mozilla.org/ko/docs/Web/API/GlobalEventHandlers/onkeyup

 

JS

 function inputNumberFormat(obj) {
     obj.value = comma(uncomma(obj.value));
 }

 function comma(str) {
     str = String(str);
     return str.replace(/(\d)(?=(?:\d{3})+(?!\d))/g, '$1,');
 }

 function uncomma(str) {
     str = String(str);
     return str.replace(/[^\d]+/g, '');
 }

replace() 메서드는 어떤 패턴에 일치하는 일부 또는 모든 부분이 교체된 새로운 문자열을 반환합니다. 그 패턴은 문자열이나 정규식(RegExp)이 될 수 있으며, 교체 문자열은 문자열이나 모든 매치에 대해서 호출된 함수일 수 있습니다.
https://developer.mozilla.org/ko/docs/Web/JavaScript/Reference/Global_Objects/String/replace