const regex = /span
:[^)]*[)];?/g;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('span
:[^)]*[)];?', 'g')
const str = `<span style="background-image: url ("http://mantis.we.intern/custom/userfiles/image/6y0eC4vzptnIxsikHs0AJA.png"); bgcolor:'red'">11111<br />
<span style="background-image: url('https:// asd asdmantis.we.intern/custom/userfiles/image/6y0eC4vzptnIxsikHs0AJA.png')">22222
<span style="background-image:url('https://fmantis.we.intern/custom/userfiles/image/6y0eC4vzptnIxsikHs0AJA.png')">3333
<span style="background-image:url( 'https://fmantis.we.intern/custom/userfiles/image/6y0eC4vzptnIxsikHs0AJA.png')">444
<span style="background-image: url ( "http://mantis.we.intern/custom/userfiles/image/6y0eC4vzptnIxsikHs0AJA.png");">555<br />
<span style="background-image: url(xx https://trk.workexpert.net/web/include/ckeditor_432/plugins/icons.png?t=E0LB& xx); >666`;
const subst = ``;
// 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