Javascript add an event listener anytime and remove an event listener anytime

Question

• On the webpage, I have a button when I click, it calls the JavaScript function.
• In this function, I show a modal dialog box, and I want to handle keystrokes only at this time. That is, when the modal dialogue is visible.

• When I close the modal dialog, I want to stop the keystroke processing.

• consider that I press the button and the sam () function is called.

  function sam () {document.onkeypress = function (e) {processKeystroke (e); }}

• So, now the function is tied to a keypress event. when a key is ever pressed, the processkeystroke function will be called. The sam function is called only after the modal dialog box is displayed.

• Now I close the modal dialog and with this I do not want the function (e) {processKes ...} to be called.

• What do I need to do to remove the connected event listener from the document. unkeypress.

• Also, I would like to have alternatives for the above approach, because the one I took from myself and I did not refer to any specific documentation, so I really look through the trial and error procedure for using event handlers or listeners.

• Therefore, when I call the sam function, I want the function to be bound to the key press event, and if I call another example of the form form closedialog (), I want the key listen function to be removed. Because I want to write the correct code, which should not consume a lot of system resources.

Answer 1

, .

 document.onkeypress = null;

, , jquery, bind (attach) unbind ( detach) , keypress.