If you really want to have this functionality in Nautilus 3.26 (which is right now the current version in Ubuntu 17.10), check out my step-by-step guide to get it in this question: Traditional search-as-you-type on newer Nautilus versions to build your own version of Nautilus with the support patched back in!
There is actually a way to get this in Nautilus 3.26 (the current
version in Ubuntu 17.10), which is building your own version from
source using a patch provided by the awesome Arch Linux community.
Luckily the great build system in Ubuntu makes this quite easy.
Here are the steps. I'll assume you'll be working in
~/bld-nautilus-typeahead. Open the terminal and do the following:
# install some necessary tools
sudo apt-get install git
# Create your work directory and go there
mkdir bld-nautilus-typeahead ; cd bld-nautilus-typeahead
# Clone the repository holding the needed patch:
git clone https://aur.archlinux.org/nautilus-typeahead.git
# Make sure the source repositories for the main archives are available:
sudo nano /etc/apt/sources.list
# If the deb-src line for the main repository (usually around line 6)
# is commented out (starts with a #)
# uncomment it (remove the #) and save the file.
sudo apt-get update
# Install the build dependencies
sudo apt-get build-dep nautilus
# Retrieve the sources for Nautilus
apt-get source nautilus
# Source should now be in the 'nautilus-3.26.0/' folder. Go there
# and Apply the patch from arch-linux
patch -p0 < ../nautilus-typeahead/nautilus-restore-typeahead.patch
# Build the package from source
dpkg-buildpackage -rfakeroot -uc -b
# This will take a little time. If everything goes well, the related packages will end up in the parent directory. Go there
# and install the required packages
sudo dpkg -i nautilus_3.26.0-0ubuntu1_amd64.deb nautilus-data_3.26.0-0ubuntu1_all.deb
Start a new Nautilus. Type some letters. Experience that feeling of
joy that happens when the file you intended gets selected.