How to save a Javascript object to file ?

Question

I need to save a complex javascript object to a file for later investigation. It is a very big object, more then 50 methods and propeties.

I can see the object and its methods and properties (and its values) in Firefox-Firebug on DOM page, but i can't save it to a file from there.

I want save the object with current values of properties, not the HTML doc. Any format of a file - HTML or JSON or anything else is good for me :)

How can I save the object?

Answer 1

Well... There is something you can do, but I can't say how ugly is. You can do something like

JSON.stringify(my_big_javascript_object) and then save the resulting JSON (plain text) in a file.

You can look at the values later using some JSON viewer, like http://jsonviewer.stack.hu/

Answer 2

You can pass the object from Your page to server-side script using AJAX like this (jQuery):

var ajax_object // Your object    

.ajax({
    type: "POST",
    url: "tofile.php",
    data: ajax_object,
});

and then write it down to a HTML file using the server-side script (example is using PHP):

// File: tofile.php

$ajax_object // Object, which You have passed using AJAX

ob_start();
print_r("<pre>".print_r($ajax_object, true)."</pre>");
$var = ob_get_contents();
ob_end_clean();
$fp = fopen('somefile.htm', 'w');
fputs($fp, $var);
fclose($fp);

The output in somefile.htm would be similar to this:

Some_Object Object
(
    [some_element] => 123
    [some_array] => Array
        (
            [element1] => 456
            [element2] => 789
            [element3] => 012
        )
)

If You are wondering how to save Your object to a file using only Javascript, without server-side language, then, I am afraid, it is not possible.

Answer 3

This works well for me.

 //Initialization of object to save var objectToSave={first:'string', second: function(){}}; //Start of saving method var textToSave='';//String to be saved var count=0; for(var i in objectToSave){ //Adding every key name + type + text value to string textToSave+=objectToSave[i].constructor.name+' '+ Object.keys(objectToSave)[count]+' = '+objectToSave[i]+'\\n'; count++; } //Saving string to file using html clicking trick var hiddenElement = document.createElement('a'); hiddenElement.href = 'data:attachment/text,' + encodeURI(textToSave); hiddenElement.target = '_blank'; hiddenElement.download = 'myFile.txt'; hiddenElement.click(); 

Result of this method is saved txt file with text:

String first = string

Function second = function (){}

Answer 4

It is possible now using the Blob API:

  function downloadObject(obj, filename){
    var blob = new Blob([JSON.stringify(obj, null, 2)], {type: "application/json;charset=utf-8"}).slice(2,-1);
    var url = URL.createObjectURL(blob);
    var elem = document.createElement("a");
    elem.href = url;
    elem.download = filename;
    document.body.appendChild(elem);
    elem.click();
    document.body.removeChild(elem);
  }

You can read more about it here: https://developer.mozilla.org/en-US/docs/Web/API/Blob

It requires that you have a webpage up with a live DOM, which should work if you are in the middle of debugging javascript on a page.