Add script to package.json via command line

.zshrc

# Reusable bash function you can add to your ~/.zshrc or ~/.bashrc file
#
# Usage: pkg-script start "node index.js"
#
function pkg-script () {
  echo $(jq --arg key "${1}" --arg val "${2}" '.scripts[$key]=$val' package.json) | jq . | > package.json
}

update_package.sh

# Add "test": "jest" to scripts object of node package
echo $(jq '.scripts.test="jest"' package.json) | jq . | > package.json

# Update package name
echo $(jq '.name="new-name"' package.json) | jq . | > package.json

# NOTE
# If you get this error: "pkg-script:1: file exists: package.json"
# run the following:
#
setopt clobber

Just jq '.scripts.test="jest"' package.json | jq . | > package.json will do