File size exceeds configured limit (2560000), code insight features not available

I am trying to work on a large Javascript file in Jetbrains WebStorm 8 and I am getting a message at the top of the editing window that says:

File size exceeds configured limit (2560000). Code insight features not available.

How can I increase the 'configured limit' to get access to all features?

In IntelliJ 2016 and newer you can change this setting from the Help menu, Edit Custom Properties (as commented by @eggplantbr).

On older versions, there's no GUI to do it. But you can change it if you edit the IntelliJ IDEA Platform Properties file:

#---------------------------------------------------------------------
# Maximum file size (kilobytes) IDE should provide code assistance for.
# The larger file is the slower its editor works and higher overall system memory requirements are
# if code assistance is enabled. Remove this property or set to very large number if you need
# code assistance for any files available regardless their size.
#---------------------------------------------------------------------
idea.max.intellisense.filesize=2500

This is built from Álvaro González's answer and How to increase IDE memory limit in IntelliJ IDEA on Mac?

Go to Help > Edit Custom Properties

Add:

idea.max.intellisense.filesize=999999

Restart the IDE.

Edit config file for IDEA: IDEA_HOME/bin/idea.properties

# Maximum file size (kilobytes) IDE should provide code assistance for.
idea.max.intellisense.filesize=60000

# Maximum file size (kilobytes) IDE is able to open.
idea.max.content.load.filesize=60000

Save and restart IDEA