use default branch by default, also support master branch alias

action.bash

@@ -14,7 +14,9 @@ set -ueE -o pipefail
 # MANUAL GITHUB CONTEXT VARIABLES
 # https://docs.github.com/en/free-pro-team@latest/actions/reference/context-and-expression-syntax-for-github-actions
 
-# GH_EVENT_NAME: ${{github.event_name}}
+# GH_DEFAULT_BRANCH: ${{ github.event.repository.default_branch }}
+# GH_MASTER_BRANCH: ${{ github.event.repository.master_branch }}
+# GH_EVENT_NAME: ${{ github.event_name }}
 
 # =====================================
 # MANUAL ENVIRONMENT VARIABLES
@@ -71,6 +73,11 @@ echo "logged into npm as: $(npm whoami)"
 # check if we wish to tag the current branch
 if test -n "${NPM_BRANCH_TAG:-}"; then
 	branch="${NPM_BRANCH_TAG%:*}"
+	if test -z "$branch" -o "$branch" = "default"; then
+		branch="${GH_DEFAULT_BRANCH}"
+	elif test "$branch" = "master"; then
+		branch="${GH_MASTER_BRANCH}"
+	fi
 	if test "$branch" = "$REPO_BRANCH"; then
 		tag="${NPM_BRANCH_TAG#*:}"
 	fi

action.yml

@@ -12,7 +12,7 @@ inputs:
     description: "Specify the token to authorize the publishing of releases to npm."
     required: true
   npmBranchTag:
-    description: "If you wish for each new commit to particular branch to be published to a particular npm tag, then specify it like so `branch:tag`, e.g. `main:next`."
+    description: "If you wish for each new commit to particular branch to be published to a particular npm tag, then specify it like so `branch:tag`, e.g. `main:next`. Omitting the branch like so `:next` will use the default branch. Using `master` as the branch will use the master branch as reported by GitHub. Using `default` as the branch will use the default branch as reported by GitHub."
     required: false
   bevryCDNToken:
     description: "If you wish to map your npm release to the Bevry CDN, then provide your Bevry CDN token."
@@ -25,7 +25,9 @@ runs:
     - run: $GITHUB_ACTION_PATH/action.bash
       shell: bash
       env:
-        GH_EVENT_NAME: ${{github.event_name}}
-        NPM_AUTH_TOKEN: ${{inputs.npmAuthToken}}
-        NPM_BRANCH_TAG: ${{inputs.npmBranchTag}}
-        BEVRY_CDN_TOKEN: ${{inputs.bevryCDNToken}}
+        GH_DEFAULT_BRANCH: ${{ github.event.repository.default_branch }}
+        GH_MASTER_BRANCH: ${{ github.event.repository.master_branch }}
+        GH_EVENT_NAME: ${{ github.event_name }}
+        NPM_AUTH_TOKEN: ${{ inputs.npmAuthToken }}
+        NPM_BRANCH_TAG: ${{ inputs.npmBranchTag }}
+        BEVRY_CDN_TOKEN: ${{ inputs.bevryCDNToken }}