Basic implementation supporting string and integers.

Author: mcollina

bench.js

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+'use strict'
+
+const benchmark = require('benchmark')
+const suite = new benchmark.Suite()
+
+const schema = {
+	"title": "Example Schema",
+	"type": "object",
+	"properties": {
+		"firstName": {
+			"type": "string"
+		},
+		"lastName": {
+			"type": "string"
+		},
+		"age": {
+			"description": "Age in years",
+			"type": "integer",
+			"minimum": 0
+		}
+	},
+	"required": ["firstName", "lastName"]
+}
+
+const obj = {
+  firstName: 'Matteo',
+  lastName: 'Collina',
+  age: 32
+}
+
+const stringify = require('.')(schema)
+
+suite.add('JSON.stringify', function () {
+  JSON.stringify(obj)
+})
+
+suite.add('fast-json-stringify', function () {
+  stringify(obj)
+})
+
+suite.on('complete', print)
+
+suite.run()
+
+function print () {
+  for (var i = 0; i < this.length; i++) {
+    console.log(this[i].toString())
+  }
+
+  console.log('Fastest is', this.filter('fastest').map('name')[0])
+}

index.js

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+'use strict'
+
+function build (schema) {
+
+  let code = `
+    'use strict'
+    let json = '{'
+  `
+
+  Object.keys(schema.properties).forEach((key, i, a) => {
+
+    const type = schema.properties[key].type
+
+    code += `
+      json += '"${key}":'
+    `
+
+    switch (type) {
+      case 'string':
+        code += `
+          json += '"' + obj.${key} + '"'
+        `
+        break;
+      case 'integer':
+        code += `
+          json += '' + obj.${key}
+        `
+        break;
+      default:
+        throw new Error(`${type} unsupported`)
+    }
+
+
+    if (i < a.length - 1) {
+      code += 'json += \',\''
+    }
+  })
+
+  code += `
+    json += '}'
+    return json
+  `
+
+  return new Function('obj', code)
+}
+
+module.exports = build

package.json

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+{
+  "name": "fast-json-stringify",
+  "version": "0.0.1",
+  "description": "Stringify your JSON at max speed",
+  "main": "index.js",
+  "scripts": {
+    "test": "standard && tap test.js"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/mcollina/fast-json-stringify.git"
+  },
+  "keywords": [
+    "json",
+    "stringify",
+    "schema",
+    "fast"
+  ],
+  "author": "Matteo Collina <[email protected]>",
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/mcollina/fast-json-stringify/issues"
+  },
+  "homepage": "https://github.com/mcollina/fast-json-stringify#readme",
+  "devDependencies": {
+    "benchmark": "^2.1.1",
+    "is-my-json-valid": "^2.13.1",
+    "standard": "^7.1.2",
+    "tap": "^6.2.0"
+  }
+}

test.js

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+'use strict'
+
+const test = require('tap').test
+const build = require('.')
+
+const example = {
+	"title": "Example Schema",
+	"type": "object",
+	"properties": {
+		"firstName": {
+			"type": "string"
+		},
+		"lastName": {
+			"type": "string"
+		},
+		"age": {
+			"description": "Age in years",
+			"type": "integer",
+			"minimum": 0
+		}
+	},
+	"required": ["firstName", "lastName"]
+}
+
+test('render a basic json', (t) => {
+  t.plan(2)
+
+  const stringify = build(example)
+  const obj = {
+    firstName: 'Matteo',
+    lastName: 'Collina',
+    age: 32
+  }
+
+  const output = stringify(obj)
+
+  t.deepEqual(JSON.parse(output), obj)
+  t.equal(output, JSON.stringify(obj))
+})