If you’re looking for a simple way to prevent users from selecting (and presumably copying) some or all of your page text, look no further than the user-select CSS property:
user-select: auto|none|text|all;
autoSets text selection automatically based on the browser settings (this is the default).
nonePrevents the user from selecting text. This is the value to use if you want to disable text selection on an element.
textAllows the user to select text.
allAllows the user to select only the entire text block. Bonus: the text block can be selected just by clicking it.
Check out an example:
Browser support: % (Source: caniuse.com)
Specification: