This example will show you how to convert JSON format string to JavaScript object and how to convert JS object back to a JSON format string. It also shows you how to write JSON string to a .json file and how to parse a JSON file content to a JavaScript object array.
1. Node JS JSON String And JS Object Convert Example Source File.
- This example contains the below source files, one .js file and two .json files.
account.json colors.json json_convert.js
- The account.json file is created in the example source code. The colors.json file is used to demo how to convert JSON file content to a javascript object array.
- The json_convert.js file is just the source node js file.
1.1 Source JS File.
- json_convert.js
// Import fs module. var fs = require("fs"); // Convert JSON format string to js object. function stringToObject(JSONString) { var jsonObject = JSON.parse(JSONString); console.log("User Name : " + jsonObject.user_name); console.log("Password : " + jsonObject.password); console.log("Email : " + jsonObject.email); // Change email property value in JS object. jsonObject.email = '[email protected]'; // Add qq and phone property in JS object. jsonObject.qq = '111111'; jsonObject.phone = '13901234567'; return jsonObject; } // Convert javascript object to json string. function objectToString(jsObject) { var jsonString = JSON.stringify(jsObject); console.log("New JSON String : " + jsonString); return jsonString; } // Write json string to json file.function writeJSONStringToFile(jsonString, filePath) { // Create a write stream. var writeStream = fs.createWriteStream(filePath, { flags : "a" }); writeStream.write(jsonString); writeStream.end(''); } // Read json object from a json text file.function jsonFileToArray(filePath){ // This code will get a json object from a .json file. var jsonObject = require(filePath); // Get color json object array. var colorArray = jsonObject.colors; var arraySize = colorArray.length; for(var i=0; i<arraySize; i++) { var colorItem = colorArray[i]; var color = colorItem.color; var category = colorItem.category; var type = colorItem.type; var code = colorItem.code; var rgba = code.rgba; var hex = code.hex; console.log("Color : " + color + " , Category : " + category + " , Type : " + type + " , Code Rgba : " + rgba + " , Hex : " + hex); } } // Create a new JSON string. var jsonString = '{"user_name" : "Jerry Zhao", "password" : "888888", "email" : ["[email protected], [email protected]"]}'; // Get the json object by above string. var jsonObject = stringToObject(jsonString); // Change the js object property and convert to json string again. var newJsonString = objectToString(jsonObject); // Write the new json string to a json file. writeJSONStringToFile(newJsonString, "account.json"); // Parse json data from a json file. jsonFileToArray('./colors.json');
- When you run the above js code, you will get the below output.
/usr/local/bin/node /Users/zhaosong/Documents/WorkSpace/dev2qa.com-example-code/JavaScriptExampleWorkspace/NodeJSWorkspace/JSONStringObjectConvert/json_convert.js User Name : Jerry Zhao Password : 888888 Email : [email protected], [email protected] New JSON String : {"user_name":"Jerry Zhao","password":"888888","email":"[email protected]","qq":"111111","phone":"13901234567"} Color : white , Category : value , Type : undefined , Code Rgba : 0,0,0,1 , Hex : #FFF Color : black , Category : hue , Type : primary , Code Rgba : 255,255,255,1 , Hex : #000 Color : red , Category : hue , Type : primary , Code Rgba : 255,0,0,1 , Hex : #FF0 Color : green , Category : hue , Type : secondary , Code Rgba : 0,255,0,1 , Hex : #0F0 Color : yellow , Category : hue , Type : primary , Code Rgba : 255,255,0,1 , Hex : #FF0 Color : blue , Category : hue , Type : primary , Code Rgba : 0,0,255,1 , Hex : #00F Process finished with exit code 0
1.2 Generated account.json File.
- account.json
{"user_name":"Jerry Zhao","password":"888888","email":"[email protected]","qq":"111111","phone":"13901234567"}
1.3 colors.json File.
- colors.json
{ "colors": [ { "color": "white", "category": "value", "code": { "rgba": [0,0,0,1], "hex": "#FFF" } },{ "color": "black", "category": "hue", "type": "primary", "code": { "rgba": [255,255,255,1], "hex": "#000" } }, { "color": "red", "category": "hue", "type": "primary", "code": { "rgba": [255,0,0,1], "hex": "#FF0" } }, { "color": "green", "category": "hue", "type": "secondary", "code": { "rgba": [0,255,0,1], "hex": "#0F0" } }, { "color": "yellow", "category": "hue", "type": "primary", "code": { "rgba": [255,255,0,1], "hex": "#FF0" } }, { "color": "blue", "category": "hue", "type": "primary", "code": { "rgba": [0,0,255,1], "hex": "#00F" } } ] }