Check Javascript file Merge is enable using Magento 2 by isMergeJsFiles() from the ConfigInterface.
To Merge JavaScript files in Magento 2 via admin panel,
Go To Admin panel,
Click Stores -> Settings -> Configuration from the left sidebar.
Click on Advanced -> Select Developer Tab,
Open the JavaScript Settings section,
Choose Yes from the Merge JavaScript Files.
Click Save Config from the top right.