# Perspective Browser and Previewer behave differently

**URL:** <https://forum.inductiveautomation.com/t/perspective-browser-and-previewer-behave-differently/79846>\
**Category:** Ignition\
**Tags:** ignition81, perspective\
**Created:** [September 29, 2023, 3:44pm UTC](https://forum.inductiveautomation.com/t/perspective-browser-and-previewer-behave-differently/79846 "2023-09-29T15:44:54Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Alex\_Fabiano](https://avatars.discourse-cdn.com/v4/letter/a/7bcc69/32.png) [@Alex\_Fabiano](https://forum.inductiveautomation.com/u/Alex_Fabiano)\
**Post date:** [September 29, 2023, 3:44pm UTC](https://forum.inductiveautomation.com/t/perspective-browser-and-previewer-behave-differently/79846/1 "2023-09-29T15:44:55Z")

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Is there any reason that a perspective binding would behave differently in the browser than it does in the designer preview mode?  
For some reason, my bindings look good in the designer, but when I go to see how they look in the browser, they are all errored saying they received null data etc.

Here is the preview

 ![Preview](https://us1.discourse-cdn.com/inductiveautomation/original/3X/f/3/f302e47f3f5f7c697b78ca3c64607df3efebe9df.png)

Here is the browser

 ![Browser](https://us1.discourse-cdn.com/inductiveautomation/original/3X/2/e/2e446398629cc8f873bfe292444137965e28d6c9.png)

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**Author:** ![cmallonee](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/cmallonee/32/6416_2.png) [@cmallonee](https://forum.inductiveautomation.com/u/cmallonee)\
**Post date:** [September 29, 2023, 4:20pm UTC](https://forum.inductiveautomation.com/t/perspective-browser-and-previewer-behave-differently/79846/2 "2023-09-29T16:20:17Z")

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Your bindings in the Designer have a value _in the Designer_, but that value is transient/ephemeral. When your _Session_ begins, it attempts to obtain a value (or references a value) which is either `null` or references a property which doesn't exist. This can be common when scripts create properties on the fly. Make sure any references your Thermometer has within the binding for `mercuryColor` are present at all times, and have default values which make sense (are non-`null`, especially if doing any transforms which would expect string or numeric types). Finally, you may want to right-click the properties in question and select the `Persistent` option. This will result in the current value in the Designer being the "starting" value in use by the component until the binding resolves.

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**Author:** ![Ali.Etezadkhah](https://avatars.discourse-cdn.com/v4/letter/a/b19c9b/32.png) [@Ali.Etezadkhah](https://forum.inductiveautomation.com/u/Ali.Etezadkhah)\
**Post date:** [September 29, 2023, 4:55pm UTC](https://forum.inductiveautomation.com/t/perspective-browser-and-previewer-behave-differently/79846/3 "2023-09-29T16:55:17Z")

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@cmallonee

I'm having a similar issue where my views look differently in the browser vs Designer preview.

 ![tanks](https://us1.discourse-cdn.com/inductiveautomation/original/3X/c/0/c09da7f4649828be1b45893a84afa2360cf39ffd.png)

The newly added sparklines show up in Designer, but when I launch the browser either from within Designer or direct, the initial view does not show the sparklines. If I refresh the page or resize, then they show up.

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**Author:** ![cmallonee](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/cmallonee/32/6416_2.png) [@cmallonee](https://forum.inductiveautomation.com/u/cmallonee)\
**Post date:** [September 29, 2023, 8:51pm UTC](https://forum.inductiveautomation.com/t/perspective-browser-and-previewer-behave-differently/79846/4 "2023-09-29T20:51:56Z")

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Running Sessions don't always pick up all chnages on save. Data/values are almost always picked, but changes to the _structure_ of the resource are often missed - or new resources. CSS changes are a good example of this: changes saved to the `stylesheet.css` resource aren't picked up in running sessions because that resource has already been loaded to the browser. Running sessions require a refresh, while new sessions will pull down the latest version of that resource.

I understand your Sparklines aren't the `stylesheet.css` resource, but they do change the structure of the page currently in use. We can't _force_ the session to take saved changes, because it would overwrite things like session properties.