This page describes some basic ways of editing map data in JOSM.
Undo / Discard changes
JOSM generally doesn’t read or write data to the OpenStreetMap database except when you ask it to, but at any time before uploading, you can discard all your changes by closing down JOSM (or by deleting the active data layer). You can also undo individual editing actions by clicking the undo toolbar button () or by pressing Ctrl+Z. So relax! If you make a mess of your editing at any point, you can always undo a few steps.
(S)elect (A)dd (D)elete
There are three main modes of operation when editing:
– (S)elect – for selecting elements, viewing/editing their tags, and moving them.
– (A)dd – for adding new nodes to create a new way, extend an existing way, or as a standalone node
– (D)elete – to delete elements
Because you will be flipping between these modes quite a lot, it’s worth remembering the keyboard shortcuts: ‘S’, ‘A’ and ‘D’
Adding a way
When creating a way, you need to think about what is currently selected.
Clear your current selection by doing ‘Edit’ menu -> ‘Unselect all’. Alternatively put JOSM into select mode (S) and click somewhere in the black background.
With nothing selected, press ‘A’ to begin adding a brand new way.
Click somewhere in black background to create a new node.
Keep clicking to draw a way with several nodes in it.
When you want to stop adding, press ‘S’ to go back to select mode.
Adding a stand-alone node
To create a standalone node, repeat the same steps above, but this time we’ll stop adding after only one node:
Clear your current selection
Press ‘A’ to begin adding
Double-click to create the node.
Press ‘S’ to go back to select mode.
appear as a strip on the right hand side of the JOSM screen, but you can show & hide each one. Do this by clicking the various buttons in the bottom-left:
They are toggle buttons, meaning you can click the same button to show the panel and then hide it and then show it again (try it) On the panels themselves, you have the option to minimise them, or un-pin a panel to have it as a separate window.
Some panels are more useful than others. You’ll definitely want to have the “properties/memberships” panel visible (label icon)
Tags are displayed in a panel called “properties/memberships” in the top-right. When you select an element, its tags will be displayed there in a table with keys on the left, and values on the right. Go into (S)elect mode and try selecting an existing way or node to see its tags. In the areas of existing map data which you downloaded, you should find a lot of tags. Some tags have quite complicated meanings, while others like the ‘name’ tag, are quite straightforward. Refer to Map Features for tag documentation (worth having a look at, but it’s quite a big list. You’re not expected to know all of these tags!)
To add a new tag, click the ‘Add’ button (not to be confused with “(A)dd mode” for adding data elements)
To edit an existing tag, double-click on it, or click once to select it and then click the ‘edit’ button.
When typing your tag into the key and value boxes, you’ll find JOSM snaps to suggested values from a drop-down. This is a time-saving feature based on all keys and values appearing within the downloaded area and all common tags that JOSM knows about.
A note on selecting: When you select elements to modify the tags on, take care to select the right thing.