knex mysql update on duplicate and replace

knex-functions.js

function upsert(table, data, update){
	if(!update) update=data;
	var insert = knex(table).insert(data).toString();
	var update = knex(table).update(update).toString().replace(/^update .* set /i, '');
	return knex.raw(insert + ' on duplicate key update ' + update);
	}

function replace(table, data){
	var insert = knex(table).insert(data).toString().replace(/^INSERT/i, 'REPLACE');
	return knex.raw(insert);
	}

Slightly better:

const update = knex.queryBuilder().update(update)

@ohjames I believe this is related to the sql statement REPLACE not UPDATE