Yarn run multiple scripts in parallel

There is a difference between using & and &&. Using & will run scripts in parallel, using && will run scripts one after the other.

package.json:

{
    "parallel": "yarn script1 & yarn script2",
    "serial": "yarn script1 && yarn script2",
    "script1": "... some script here",
    "script2": "... some there script here"
}