const regex = /\d+/\d+/\d+/gm;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('\\d+\/\\d+\/\\d+', 'gm')
const str = `interface gpon_olt-1/1/1 onu 1 type ZTE-OMC3 sn ZTEGC0CD5938
interface gpon_olt-1/1/1 onu 2 type ZTE-F612 sn ZTEGC8BF978F
interface gpon_olt-1/1/1 onu 3 type ZTE-OMC3 sn ZTEGC8653DA1
interface gpon_olt-1/1/1 onu 4 type ZTE-OMC3 sn ZTEGC4BC9D80
interface gpon_olt-1/1/1 onu 5 type ZTE-F670 sn ZTEGCE8DA5F5
interface gpon_olt-1/1/1 onu 7 type ZTE-F670 sn ZTEGC8509BBE
interface gpon_olt-1/1/1 onu 8 type ZTE-F670 sn ZTEGC8B65274`;
const subst = `\1`;
// 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