Which programming language should I use for building an interactive 'flowchart' on my website? [on hold]

I have a website with a login-system and so on, and now I want to create a page for the users where they can create their own sort of flowchart that can be seen by others. Basically what I want is:

• a button that, when pressed, creates a new bubble a background 'grid' of points so that each new bubble is placed only on the points in an ordered manner
• the possibility to add a new bubble from another bubble so that they are connected by a line
• the possibility to add lines between existing bubbles
• the ability to move the bubbles anywhere on the grid, as long as there isn't another bubble on the point they're placed (and the lines to adjust to their new position)
• ability to delete one bubble or an entire branch of bubbles
• ability to add a description to bubbles + a description box in the corner so that when a bubble is clicked (after editing is done), a description of it will be shown in the box
• ability to change colour of bubbles
• etc.

Obviously these flowcharts need to be saved so that when the user logs out and in again, they're still there. Can this be done in Javascript, or is there another programming language or something else that would make it a lot easier?