rails - “WARNING: Can't verify CSRF token authenticity” for json devise requests

Question

How can I retrieve the CSRF token to pass with a JSON request?

I know that for security reasons Rails is checking the CSRF token on all the request types (including

Answer 1

This answer is better.

You get to keep the CSRF-TOKEN validation with no extra effort (the token is appended) before any XMLHttpRequest send. No JQuery, no nothing just copy/paste and refresh.

Simply add this code.

(function() {
    var send = XMLHttpRequest.prototype.send,
        token = $('meta[name=csrf-token]').attr('content');
    XMLHttpRequest.prototype.send = function(data) {
        this.setRequestHeader('X-CSRF-Token', token);
        return send.apply(this, arguments);
    };
}());