Full-text search would be pretty dumb if you had to build the index every time, and Lunr makes it really easy to serialize and deserialize the index itself:
var serializedIndex = JSON.stringify(index1.toJSON())
var deserializedIndex = JSON.parse(serializedIndex)
var index2 = lunr.Index.load(deserializedIndex)
Tombé sur ça : http://lunrjs.com/