How can I read a JSON in the script-tag from JavaScript?
JavascriptJsonJavascript Problem Overview
I have a dynamically generated page where I want to use a static JavaScript and pass it a JSON string as a parameter. I have seen this approach used by Google (see Google's +1 Button: How do they do it?).
But how should I read the JSON string from the JavaScript?
<html>
<head>
<script src="jquery-1.6.2.min.js"></script>
<script src="myscript.js">{"org": 10, "items":["one","two"]}</script>
</head>
<body>
Hello
</body>
</html>
In this JavaScript I would like to use the JSON argument {"org": 10, "items":["one","two"]} from the HTML document. I don't know if it's best to do it with jQuery or without.
$(function() {
// read JSON
alert("the json is:")
})
Javascript Solutions
Solution 1 - Javascript
I would change the script declaration to this:
<script id="data" type="application/json">{"org": 10, "items":["one","two"]}</script>
Note type and id fields. After that
var data = JSON.parse(document.getElementById('data').textContent);
will work just fine in all browsers.
The type="application/json" is needed to prevent browser from parsing it while loading.
And the reason why we use textContent instead of innerHTML or innerText to read the raw Json text is because innerHTML tries to parse the contents as HTML which will lead to slower performance and possible parsing bugs and XSS attacks, and innerText won't grab the raw text and will instead look for human-visible text, whereas textContent grabs the pure text as-is (which is what you want). See https://developer.mozilla.org/en-US/docs/Web/API/Node/textContent for more details about why innerHTML and innerText are bad.
Solution 2 - Javascript
I ended up with this JavaScript code to be independent of jQuery.
var jsonElement = document.getElementById('json-script-tag');
var myObject = JSON.parse(jsonElement.textContent);
Solution 3 - Javascript
To read JSON in <script id="myJSON"> use
var manifest= document.getElementById('myJSON').innerHTML; //sets manifest to the text in #myJSON
manifest= JSON.parse(manifest) //Converts text into JSON
You can also use methods to point to the script like document.scripts[0]
//var manifest= JSON.parse(document.getElementById('myJSON').innerHTML); /*Shortend of 2&3*/
var manifest= document.getElementById('myJSON').innerHTML; //Gets text in #myJSON
manifest= JSON.parse(manifest) //Converts it into JSON
document.getElementById('test').innerHTML= manifest.name+ '<br/>'+ manifest.otherOptions; //Displays it
console.log('manifest')
console.log(manifest);
<head>
<script type="application/json" id="myJSON">
{"name":"Web Starter Kit", "otherOptions":"directly here"}
</script>
</head>
<body>
<p id="test"></p>
</body>
Solution 4 - Javascript
JSON.parse($('script[src="mysript.js"]').html());
or invent some other method to identify the script.
Maybe instead of .html() you might need .text(). Not sure. Try them both.