const regex = /^.*?(IDC\w*)[\s\S]*?(?:$|(,\n.*$))(\n|$)/gmi;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('^.*?(IDC\\w*)[\\s\\S]*?(?:$|(,\\n.*$))(\\n|$)', 'gmi')
const str = ` LTEXT "Width",IDC_WIDTH_TEXT,203,74,22,10
EDITTEXT IDC_WIDTH_IN,244,73,57,12,ES_AUTOHSCROLL | WS_GROUP
CONTROL "Manually scale instances and paper",IDC_RAD_PSCALE_KEYIN,
"Button",BS_AUTORADIOBUTTON | WS_GROUP | WS_TABSTOP,15,89,132,10
CONTROL "Keep drawing instance scale 1.0",IDC_RAD_PSCALE_AUTO,
"Button",BS_AUTORADIOBUTTON,15,104,123,10
CONTROL "Keep drawing paper scale 1.0",IDC_RAD_ISCALE_AUTO,
"Button",BS_AUTORADIOBUTTON,15,119,118,10`;
const subst = `$1\n`;
// The substituted value will be contained in the result variable
const result = str.replace(regex, subst);
console.log('Substitution result: ', result);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions