NodeJS : Sending application/json data with navigation.sendBeacon, preflight succeedes but not post

NodeJS : Sending application/json data with navigation.sendBeacon, preflight succeedes but not post
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On Google, Search for "hows tech developer connect"

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NodeJS : Sending application/json data with navigation.sendBeacon, preflight succeedes but not post
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Sending but preflight : succeedes data not post NodeJS with application/json navigation.sendBeacon,