N3 writer doesn't prefix correctly

[gezever]

const N3 = require('n3');
const { DataFactory } = N3;
const { namedNode, quad } = DataFactory;
const writer = new N3.Writer({ prefixes: {   ex1: 'http://example.org/' } });
writer.addQuad(
    namedNode('http://example.org/s1'),
    namedNode('http://example.org/p'),
    namedNode('http://example.org/1')
);
writer.addQuad(quad(
    namedNode('http://example.org/s2'),
    namedNode('http://example.org/p'),
    namedNode('http://example.org/_1')
));
writer.addQuad(quad(
    namedNode('http://example.org/s3'),
    namedNode('http://example.org/p'),
    namedNode('http://example.org/v1.0')
));
writer.end((error, result) => console.log(result));

expected results:

@prefix ex1: <http://example.org/>.

ex1:s1  ex1:p   ex1:1 .
ex1:s2  ex1:p   ex1:_1 .
ex1:s3  ex1:p   ex1:v1.0 .

results:

@prefix ex1: <http://example.org/>.

ex1:s1 ex1:p <http://example.org/1>.
ex1:s2 ex1:p ex1:_1.
ex1:s3 ex1:p <http://example.org/v1.0>.

[gezever]

@TallTed
I edited the issue.

[RubenVerborgh]

N3.js does not strive for the shortest form; it adds some prefixes but not exhaustively, and this for performance reasons. That said, in this case, the regex can easily be adjusted, presumably without performance impact.