diff --git a/poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-fetching.rst b/poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-fetching.rst
index f9d9e61..4dfb788 100644
--- a/poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-fetching.rst
+++ b/poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-fetching.rst
@@ -688,6 +688,8 @@
 
 It can also be used when setting mirrors definitions using the :term:`PREMIRRORS` variable.
 
+.. _crate-fetcher:
+
 Crate Fetcher (``crate://``)
 ----------------------------
 
@@ -704,6 +706,80 @@
 
    SRC_URI = "crate://crates.io/glob/0.2.11"
 
+.. _npm-fetcher:
+
+NPM Fetcher (``npm://``)
+------------------------
+
+This submodule fetches source code from an
+`NPM <https://en.wikipedia.org/wiki/Npm_(software)>`__
+Javascript package registry.
+
+The format for the :term:`SRC_URI` setting must be::
+
+   SRC_URI = "npm://some.registry.url;OptionA=xxx;OptionB=xxx;..."
+
+This fetcher supports the following parameters:
+
+-  *"package":* The NPM package name. This is a mandatory parameter.
+
+-  *"version":* The NPM package version. This is a mandatory parameter.
+
+-  *"downloadfilename":* Specifies the filename used when storing the downloaded file.
+
+-  *"destsuffix":* Specifies the directory to use to unpack the package (default: ``npm``).
+
+Note that NPM fetcher only fetches the package source itself. The dependencies
+can be fetched through the `npmsw-fetcher`_.
+
+Here is an example URL with both fetchers::
+
+   SRC_URI = " \
+       npm://registry.npmjs.org/;package=cute-files;version=${PV} \
+       npmsw://${THISDIR}/${BPN}/npm-shrinkwrap.json \
+       "
+
+See :yocto_docs:`Creating Node Package Manager (NPM) Packages
+</dev-manual/common-tasks.html#creating-node-package-manager-npm-packages>`
+in the Yocto Project manual for details about using
+:yocto_docs:`devtool <https://docs.yoctoproject.org/ref-manual/devtool-reference.html>`
+to automatically create a recipe from an NPM URL.
+
+.. _npmsw-fetcher:
+
+NPM shrinkwrap Fetcher (``npmsw://``)
+-------------------------------------
+
+This submodule fetches source code from an
+`NPM shrinkwrap <https://docs.npmjs.com/cli/v8/commands/npm-shrinkwrap>`__
+description file, which lists the dependencies
+of an NPM package while locking their versions.
+
+The format for the :term:`SRC_URI` setting must be::
+
+   SRC_URI = "npmsw://some.registry.url;OptionA=xxx;OptionB=xxx;..."
+
+This fetcher supports the following parameters:
+
+-  *"dev":* Set this parameter to ``1`` to install "devDependencies".
+
+-  *"destsuffix":* Specifies the directory to use to unpack the dependencies
+   (``${S}`` by default).
+
+Note that the shrinkwrap file can also be provided by the recipe for
+the package which has such dependencies, for example::
+
+   SRC_URI = " \
+       npm://registry.npmjs.org/;package=cute-files;version=${PV} \
+       npmsw://${THISDIR}/${BPN}/npm-shrinkwrap.json \
+       "
+
+Such a file can automatically be generated using
+:yocto_docs:`devtool <https://docs.yoctoproject.org/ref-manual/devtool-reference.html>`
+as described in the :yocto_docs:`Creating Node Package Manager (NPM) Packages
+</dev-manual/common-tasks.html#creating-node-package-manager-npm-packages>`
+section of the Yocto Project.
+
 Other Fetchers
 --------------
 
@@ -713,8 +789,6 @@
 
 -  Mercurial (``hg://``)
 
--  npm (``npm://``)
-
 -  OSC (``osc://``)
 
 -  Secure FTP (``sftp://``)
diff --git a/poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.rst b/poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.rst
index af4b135..3378216 100644
--- a/poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.rst
+++ b/poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.rst
@@ -195,22 +195,45 @@
 Setting a weak default value (??=)
 ----------------------------------
 
-It is possible to use a "weaker" assignment than in the previous section
-by using the "??=" operator. This assignment behaves identical to "?="
-except that the assignment is made at the end of the parsing process
-rather than immediately. Consequently, when multiple "??=" assignments
-exist, the last one is used. Also, any "=" or "?=" assignment will
-override the value set with "??=". Here is an example::
+The weak default value of a variable is the value which that variable
+will expand to if no value has been assigned to it via any of the other
+assignment operators. The "??=" operator takes effect immediately, replacing
+any previously defined weak default value. Here is an example::
 
-   A ??= "somevalue"
-   A ??= "someothervalue"
+   W ??= "x"
+   A := "${W}" # Immediate variable expansion
+   W ??= "y"
+   B := "${W}" # Immediate variable expansion
+   W ??= "z"
+   C = "${W}"
+   W ?= "i"
 
-If ``A`` is set before the above statements are
-parsed, the variable retains its value. If ``A`` is not set, the
-variable is set to "someothervalue".
+After parsing we will have::
 
-Again, this assignment is a "lazy" or "weak" assignment because it does
-not occur until the end of the parsing process.
+   A = "x"
+   B = "y"
+   C = "i"
+   W = "i"
+
+Appending and prepending non-override style will not substitute the weak
+default value, which means that after parsing::
+
+   W ??= "x"
+   W += "y"
+
+we will have::
+
+   W = " y"
+
+On the other hand, override-style appends/prepends/removes are applied after
+any active weak default value has been substituted::
+
+   W ??= "x"
+   W:append = "y"
+
+After parsing we will have::
+
+   W = "xy"
 
 Immediate variable expansion (:=)
 ---------------------------------