JavaScript替换，忽略第一个匹配项

Question

I have the following script in javascript

var idText;
var idText1;
idText = "This_is_a_test";
idText1 = idText.replace(/_/g, " ");
alert(idText1);

When I show idText1, it replaces all of the underscores and puts in a space where they were. However, I am trying to keep the very first underscore, so I get "This_is a test". Is this possible at all?

Answer 1

It is certainly possible, here is one option:

var n = 0;
idText1 = idText.replace(/_/g, function($0) {
    n += 1;
    return n === 1 ? $0 : " ";
});

This uses a callback for the replacement that increments a counter for each match, and replaces the first match with the original text by checking the value of that counter.