Make these changes to augment your local npm autocompletion to include autocomplete for `npm install`

.npm_install_autocomplete

#!/usr/bin/env bash #adding this to force silly gist highlighting 

# If you are already using npm autocompletion via (https://docs.npmjs.com/cli/completion), I assume that you have some code in
# your .bashrc/.zshrc file. Follow the instruction below to avoid clobbering the npm autocomplete script.


#####################
#### FOR BASH change THIS (in your .bashrc file)
#####################
  IFS=$'\n' COMPREPLY=($(COMP_CWORD="$cword" \
                           COMP_LINE="$COMP_LINE" \
                           COMP_POINT="$COMP_POINT" \
                           npm completion -- "${words[@]}" \
                           2>/dev/null)) || return $?

### TO THIS ( We added an if block, and wrapped the existing in the else block ) ###############################

	# if your npm command includes `install`
	if [[ ${words[@]} =~ 'install' ]]; then
		local cur=${COMP_WORDS[COMP_CWORD]}

		# supply autocomplete words from `~/.npm`, with $cur being value of current expansion like 'expre'
		COMPREPLY=( $( compgen -W "$(ls ~/.npm )" -- $cur ) )
    else
        IFS=$'\n' COMPREPLY=($(COMP_CWORD="$cword" \
          COMP_LINE="$COMP_LINE" \
          COMP_POINT="$COMP_POINT" \
          npm completion -- "${words[@]}" \
          2>/dev/null)) || return $?
	fi

#####################
#### FOR ZSH change THIS (in your .zshrc file)
#####################
    IFS=$'\n' COMPREPLY=($(COMP_CWORD="$cword" \
                           COMP_LINE="$COMP_LINE" \
                           COMP_POINT="$COMP_POINT" \
                           npm completion -- "${words[@]}" \
                           2>/dev/null)) || return $?

### TO THIS ( We added an if block, and wrapped the existing in the else block ) ###############################

	# if your npm command includes `install`
	if [[ ${words} =~ 'install' ]]; then
	    compadd -- $(COMP_CWORD=$((CURRENT-1)) \
		COMP_LINE=$BUFFER \
		COMP_POINT=0 \
		ls ~/.npm -- "${words[@]}" \
	    2>/dev/null)

	else
	    compadd -- $(COMP_CWORD=$((CURRENT-1)) \
		COMP_LINE=$BUFFER \
		COMP_POINT=0 \
		npm completion -- "${words[@]}" \
		2>/dev/null)
	fi