Angular-cli 8 - Is it possible to build only on es2015?

If you update your browserslist accordingly (.browserlistrc-file or browserlist-Array in package.json) and only add browsers which are capable of ES2015, only one build should be created.

For example, when using

"browserslist": [
  "> 5%"
]

I only get one build instead of two builds for es5 and es2015. (Okay, to be fair, only chrome makes it into the list with > 5%...)

(You can also check with npx browserslist for a list of browsers that would currently be supported with your project setup. Also, see the "Differential Loading"-part here for a detailed explanation.)

You need to add the line defaults and put the word not at the begin of every line below in the file browserlist. For example:

defaults
not > 0.5%
not last 2 versions
not Firefox ESR
not dead
not IE 9-11 # For IE 9-11 support, remove 'not'.

After that you can check changes by the command npx browserslist. It should print nothing.