Replace rear navigation in JavaScript regular expression

const regfix1 = /(?<=\s\S*)\s*/gi;

In JavaScript, we created a regular expression like this to assign all spaces except the first space in the specified string.

However, the execution environment does not support backward search (?<=) grammar.

So I asked if there is a regular expression that can replace all regular expressions using back search, or if there is another expression that can specify the above conditions, "all spaces except the first space."