close delete instance

src/database.js

@@ -195,6 +195,7 @@ DB.prototype.close = function () {
   if (this.db) {
     this.db.close()
     this.db = undefined
+    if (this === instance) instance = null
   }
   return this
 }
@@ -330,8 +331,8 @@ DB.prototype.update = function (table, data, where, whiteList) {
   let parameter = []
 
   // Build data part of the query
-  let setStringBuilder = []
-  for (let keyOfData in data) {
+  const setStringBuilder = []
+  for (const keyOfData in data) {
     const value = data[keyOfData]
     // don't set undefined and only values in an optional whitelist
     if (value !== undefined && (!whiteList || whiteList.includes(keyOfData))) {
@@ -348,12 +349,12 @@ DB.prototype.update = function (table, data, where, whiteList) {
   // Build where part of query
   sql += ' WHERE '
   if (Array.isArray(where)) {
-    let [whereTerm, ...whereParameter] = where
+    const [whereTerm, ...whereParameter] = where
     sql += whereTerm
     parameter = [...parameter, ...whereParameter]
   } else if (typeof where === 'object') {
-    let whereStringBuilder = []
-    for (let keyOfWhere in where) {
+    const whereStringBuilder = []
+    for (const keyOfWhere in where) {
       const value = where[keyOfWhere]
       if (value !== undefined) {
         parameter.push(value)
@@ -486,7 +487,7 @@ function createInsertOrReplaceStatement (insertOrReplace, table, data, whiteList
 
   // Build start of where query
   let sql = `${insertOrReplace} INTO \`${table}\` (\`${fields.join('`,`')}\`) VALUES `
-  let parameter = []
+  const parameter = []
   let addComma = false
 
   data.forEach(rowData => {
@@ -524,7 +525,7 @@ DB.prototype.migrate = function ({ force, table = 'migrations', migrationsPath =
   //   { id: 2, name: 'feature', fielname: '002-feature.sql', up: ..., down: ... }
   migrations.map(migration => {
     const filename = path.join(location, migration.filename)
-    let data = fs.readFileSync(filename, 'utf-8')
+    const data = fs.readFileSync(filename, 'utf-8')
     const [up, down] = data.split(/^--\s+?down\b/mi)
     if (!down) {
       const message = `The ${migration.filename} file does not contain '-- Down' separator.`