Add and modify watch expressions
Watch expressions are expressions that evaluate in the global scope normally but evaluate in the local scope when the debugger is paused. Watch expressions can be found in the Debugger tab and are useful when you need to frequently check the value of specific variables or expressions while debugging.
Watch expressions automatically refresh when the debugger pauses or takes a step, are re-evaluated in the current scope where execution is paused, and persist across page loads. If an expression is not valid in the current scope, it returns an error.
Add a watch expression
Click the Add Watch Expression (+) button in the right sidebar in the Debugger tab and enter the expression you want to watch.
Remove a watch expression
Control-click on a watch expression and choose Remove Watch Expression from the pop-up menu.
Remove all watch expressions
Click the Clear Watch Expressions trash button at the top of the right sidebar in the Debugger tab.
Refresh watch expression results
When the debugger is not paused, click the Refresh button at the top of the right sidebar in the Debugger tab.
Watch expressions are particularly useful in conjunction with the Copy Path to Property command, available by Control-clicking on any DOM tree item or object preview.