JavaScript: Create and save file

Question

I have data that I want to write to a file, and open a file dialog for the user to choose where to save the file. It would be great if it worked in all browsers, but it has to work in Chrome. I want to do this all client-side.

Basically I want to know what to put in this function:

saveFile: function(data)
{
}

Where the function takes in data, has the user select a location to save the file, and creates a file in that location with that data.

Using HTML is fine too, if that helps.

Answer 1

A very minor improvement of the code by Awesomeness01 (no need for anchor tag) with addition as suggested by trueimage (support for IE):

// Function to download data to a file
function download(data, filename, type) {
    var file = new Blob([data], {type: type});
    if (window.navigator.msSaveOrOpenBlob) // IE10+
        window.navigator.msSaveOrOpenBlob(file, filename);
    else { // Others
        var a = document.createElement("a"),
                url = URL.createObjectURL(file);
        a.href = url;
        a.download = filename;
        document.body.appendChild(a);
        a.click();
        setTimeout(function() {
            document.body.removeChild(a);
            window.URL.revokeObjectURL(url);  
        }, 0); 
    }
}

Tested to be working properly in Chrome, FireFox and IE10.

In Safari, the data gets opened in a new tab and one would have to manually save this file.