How to read an external local JSON file in JavaScript?

For reading the external Local JSON file (data.json) using javascript, first create your data.json file:

data = '[{"name" : "Ashwin", "age" : "20"},{"name" : "Abhinandan", "age" : "20"}]';

Then,

1. Mention the path of the json file in the script source along with the javascript file

    <script type="text/javascript" src="data.json"></script>
    <script type="text/javascript" src="javascript.js"></script>
   

2. Get the Object from the json file

    var mydata = JSON.parse(data);
    alert(mydata[0].name);
    alert(mydata[0].age);
    alert(mydata[1].name);
    alert(mydata[1].age);
   

For more information, see this reference.

You cannot make a AJAX call to a local resource as the request is made using HTTP.

A workaround is to run a local webserver, serve up the file and make the AJAX call to localhost.

In terms of helping you write code to read JSON, you should read the documentation for jQuery.getJSON():

http://api.jquery.com/jQuery.getJSON/

The loading of a .json file from harddisk is an asynchronous operation and thus it needs to specify a callback function to execute after the file is loaded.

function readTextFile(file, callback) {
    var rawFile = new XMLHttpRequest();
    rawFile.overrideMimeType("application/json");
    rawFile.open("GET", file, true);
    rawFile.onreadystatechange = function() {
        if (rawFile.readyState === 4 && rawFile.status == "200") {
            callback(rawFile.responseText);
        }
    }
    rawFile.send(null);
}

//usage:
readTextFile("/Users/Documents/workspace/test.json", function(text){
    var data = JSON.parse(text);
    console.log(data);
});

This function works also for loading a .html or .txt files, by overriding the mime type parameter to "text/html", "text/plain" etc.