Command block check chest

I want to make a shop where the player must hold a item and then click a button, and what I want to do is a "test for" like command to check if the item in the players hand matches the item in slot 0 in the chest. Is there a way to do that thanks.
or I could just check if the item is in the players inventory. :)
Best Answer
You cannot compare the two items in the sense of
Chest == Hand
However you can do something more like
Chest == X and Hand == X therefor Chest == Hand
You can check what is in the hand using {SelectedItem:{Item Tag}} (see more at http://minecraft.gamepedia.com/Player.dat)
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How can you tell if a chest is empty in Minecraft?
You can test whether there is a certain block at a specific location in the game using the /testforblock command in Minecraft. TIP: Starting in Minecraft Java Edition (PC/Mac) 1.13, the /testforblock command was removed from the Java Edition version of the game.How do you check blocks with command blocks?
By holding \u21e7 Shift and double-clicking while holding an item, all items of a type clicked on will be moved into or out of the chest.how to detect item in a chest! I minecraft chest detection tutorial 1.16.5!
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Answer 2
No, you cannot compare items in inventories. You probably want to check for the specific item in the command.
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