On this page:
- Evaluating Arbitrary Expressions
- Evaluating Expressions in the Editor
- Evaluating Variables in the Console Pane
While using the Expression Evaluation feature, be aware of the following:
- A method can be invoked within the Expression Evaluation dialog only if the debugger has stopped at a breakpoint, but has not been paused.
- Expression Evaluation can only be "single-level". In other words, if WebStorm stops at a breakpoint within a method called from the Expression Evaluation, you cannot use the Expression Evaluation feature again.
Evaluating Arbitrary Expressions
- Open the Evaluate Expression dialog box in one of the following ways:
- Choose on the main menu.
- To have a specific variable evaluated, select it on the Variables pane, then choose or pressAlt+F8.
- In the
dialog box, specify the expression to evaluate. Do one of the following:
In the Expression field, type the expression in question or choose one of the previously evaluated expressions
from the drop-down list.
If you have selected a specific variable on the Variables pane, this variable will be displayed in the Expression text box.
- To evaluate a code fragment, click the Code Fragment Mode button and
fill in the Code Fragment text box.
To return to the original mode, click the Expression mode button.
- In the Expression field, type the expression in question or choose one of the previously evaluated expressions from the drop-down list.
- Click the Evaluate button. The Result read-only field shows the evaluation output. If the specified expression cannot be evaluated, the Result field explains the reason.
Evaluating Expressions in the Editor
Note that during a debugger session, the value of any expression is shown in the tooltip every time you hover your mouse pointer over it. If an expression contains children, clicking expands the node and displays all children.
However, Quick evaluate expression helps you view the expression value using the keyboard only.
There are two ways to quickly evaluate an expression:
By using the Show Value On Selection Change
- In the Debug tool window toolbar click the Settings icon and select the Show Value On Selection Change option from the popup menu.
Select a code fragment with the mouse, or by clicking
Ctrl+W. A tooltip with the expression value automatically appears under the selection and changes each time you change the selection:
By invoking the tooltip with the expression value manually:
- Place the caret at the desired location, or select an expression to be evaluated.
- Press Ctrl+Alt+F8. The tooltip with the expression value appears under the selected expression.
Evaluating Variables in the Console Pane
This can be done in several ways:
- Select the variable in question in the Variables pane and choose
Evaluate in Console on the context menu of the selection.
When you switch to the Console pane, the variable name is shown as input (
<) and its value is marked with
- Alternatively you can type the name of any variable in the Console manually and press Enter to have its value displayed.
- To evaluate a previously evaluated variable without searching for it in the Variables pane, find the variable in question using the Up and Down arrows on you keyboard and press Enter.