SharePoint 2013 comes with the new Script Editor WebPart which can be used on Wiki/WebPart/Publishing Pages to add Script Code to the page. Using it is fairly simple: add it to the page from the WebPart Catalog.
BUT MySites for example don’t contain the Script Editor WebPart in the catalog:
To bring the Script Editor WebPart to the MySite WebPart Catalog (and therefore to all of the subsites like Blog etc.), you can
- download the file “MSScriptEditor.webpart” from any “Web parts” Gallery in your content sites (Settings | Site Settings)
Now go to the “Web parts” Gallery on your MySite and upload the previously saved file “MSScriptEditor.webpart” to the gallery - change Title and Description and Group as needed ;-)
Et voilà - you can use the ScriptEditor WebPart throughout your MySite…