# \[SOLVED\] Open window in script tag changed

**URL:** <https://forum.inductiveautomation.com/t/solved-open-window-in-script-tag-changed/63653>\
**Category:** Ignition\
**Tags:** vision, ignition81\
**Created:** [August 31, 2022, 8:30pm UTC](https://forum.inductiveautomation.com/t/solved-open-window-in-script-tag-changed/63653 "2022-08-31T20:30:10Z")\
**Posts on this page:** 1\
**Showing post:** 14

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**Author:** ![paul-griffith](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/paul-griffith/32/37249_2.png) [@paul-griffith](https://forum.inductiveautomation.com/u/paul-griffith)\
**Post date:** [September 28, 2022, 3:48pm UTC](https://forum.inductiveautomation.com/t/solved-open-window-in-script-tag-changed/63653/14 "2022-09-28T15:48:27Z")

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`getPreviousValue` can return `null` if the `initialChange` flag is set:

> [@Gateway scripting - previous value](https://forum.inductiveautomation.com/t/gateway-scripting-previous-value/64568/2):
>
> What doesn’t work about it? Keep in mind the first time the script executes there is no previous value, so it will be null / Python None, which you need to check for before you try to access its value component.

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