How to pause script execution in Developers console

As katspaugh mentions in their comment:

F8

This only works for me from the Sources tab of the Developer Tools window in Chrome 59.0.3071.115 (on Mac OS X).

You can write a pause code yourself. Pause javascript excution using debugger. In the chrome console, run:

window.addEventListener('keydown', function(event) { 
  if (event.defaultPrevented) {
    return; // Should do nothing if the default action has been cancelled
  }
  let handled = false;
  if (event.keyCode == 121) {
    handled = true;
    debugger;  // 121 is the keyCode of F10
  }
  if (handled) {
    // Suppress "double action" if event handled
    event.preventDefault();
  }
});

Highlight element with inspector

Hit F10

You are looking for "breakpoints".

Which browser are you using?

Chrome supports breakpoints right away in its developer tools:
F12 (or Ctrl-Shift-I), "Script" tab, select script from dropdown, click the line number.
Update:
On PC: F12 or Ctrl+Shift+I / On Mac: Cmd+Alt+I
select "Sources" tab, select script from the file pane on the left, click the line number.

In Firefox use the Firebug extension:
On PC and Mac: F12,
"Script" tab, activate & reload if needed, select script from dropdown, click line number.

When your Javascript pauses at a breakpoint, both browsers offer you the usual debugging tools to single step through the code, inspect & change variable values, watch expressions,...