Creating a javascript cookie

Question

I am attempting to create a cookie. I suspect that my cookie isnt saving or being retrieved properly. What am I doing wrong?

I tried 2 methods to save this cookie:

Cookie gets saved in this function:

function(config) {
    var config_copy = JSON.parse(JSON.stringify(config));
    setCookie('key',config_copy);
}

Use setCookie();

function(config) {
    var config_copy = JSON.parse(JSON.stringify(config));
    setCookie();
}

Then trigger this function:

function setCookie(key,config_copy){
    document.cookie = key + "=" + config_copy;
    console.log("cookie saved");
    console.log(config_copy);
}

console.log(config_copy); returns undefined in the console.

How would I correctly save the value of config_copy into a JavaScript cookie?

If you want to check your cookies you can open up your developer tools and either inspect the value in document.cookie by typing that in console. A question, in method 2 how would you expect the arg's key, config_copy to be defined in your setCookie function if you don't pass them? — scrappedcola
– scrappedcola, Commented Aug 6, 2015 at 18:06
davidbcalhoun.com/2009/passing-data-to-functions-in-javascript if you have to ask you really need to read a basic tutorial on functions in javascript. — scrappedcola
– scrappedcola, Commented Aug 6, 2015 at 18:09

Barmar · Accepted Answer · 2015-08-06 18:37:00Z

1

JSON.parse() returns an object, not a JSON string. You should put the JSON string into the cookie, not the result of JSON.parse.

function saveConfig(config) {
    var config_copy = JSON.stringify(config);
    setCookie("key", config_copy);
}

Otherwise, you'll just set the cookie to [Object object].

answered Aug 6, 2015 at 18:37

Barmar

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score 1 · Accepted Answer · 2015-08-06 19:06:36Z

Document.cookie only accepts primitive values, if you pass an object it calls Object.toString() which returns [ object Object ].

You have too options for storing an object in cookie form.

Multiple cookies from an object's properties

If you want to make a cookie out of each property of an object, you have to loop through the object and create a cookie out of each property.

var saveConfig = function(config) {
    var cookies = [];
    for(var i in config)
        cookies.push(document.cookie = i + '=' + config[i]);
    return cookies;
}
saveConfig({hello: 'world', foo: 'bar'});
console.log(document.cookie);

Outputs: hello=world; foo=bar;

One cookie from an object converted to a string

You can convert the object to a string and store it in one cookie using JSON.stringify().

var saveConfig = function(config) {
    return document.cookie = 'config=' + JSON.stringify(config);
}
saveConfig({hello: 'world', foo: 'bar'});
console.log(document.cookie);

Outputs: config={"hello":"world","foo":"bar"};

lem2802 · Accepted Answer · 2015-08-06 18:33:42Z

0

In your second "option" you have to send a value for the parameters like this:

function(config) {
    var config_copy = JSON.parse(JSON.stringify(config));
    setCookie("key", config_copy);
}

if you call it without the parameters, they will have an undefined value

answered Aug 6, 2015 at 18:33

lem2802

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Comments

Scott · Accepted Answer · 2015-08-06 18:35:36Z

0

You need to pass your variables to setCookie() in order for the function to use them.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Functions#Calling_functions

answered Aug 6, 2015 at 18:35

Scott

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Creating a javascript cookie

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