support custom format function

index.js

@@ -1,5 +1,7 @@
 'use strict';
 
+const customFormat = {};
+
 exports.divider = ' ';
 
 // decide the value should be mask
@@ -23,6 +25,9 @@ function isObject(value) {
 }
 
 function toString(k, v, level) {
+  if (customFormat[k]) {
+    return customFormat[k](v);
+  }
   if (exports.isSecret && exports.isSecret(k)) {
     if (isString(v)) {
       return `${k}="***"`;
@@ -71,4 +76,14 @@ function stringify(json, level) {
   return format(json, level || exports.maxLevel);
 }
 
+function addFormat(key, fn) {
+  customFormat[key] = fn;
+}
+
+function removeFormat(key) {
+  delete customFormat[key];
+}
+
 exports.json = stringify;
+exports.addFormat = addFormat;
+exports.removeFormat = removeFormat;

package.json

@@ -1,6 +1,6 @@
 {
   "name": "simple-stringify",
-  "version": "1.1.3",
+  "version": "1.2.0",
   "description": "stringify json on top attr",
   "author": "Tree Xie <vicansocanbico@gmail.com>",
   "repository": {

test/index.js

@@ -23,6 +23,14 @@ describe('Simple-stringify', () => {
       console.dir('test');
     },
   };
+
+  it('add custom format', () => {
+    stringify.addFormat('myCustomKey', v => `myCustomKey="length(${v.length})"`);
+    assert.equal(stringify.json({
+      myCustomKey: 'abcd',
+    }), 'myCustomKey="length(4)"');
+    stringify.removeFormat('myCustomKey');
+  });
 
   it('format json success', () => {
     assert.equal(stringify.json(data), 'no=123 mobile=null addresss=undefined disabled=false name="tree.xie" keywords=[] infos={} fn=function');