I want to use it to code XMl ,how to set ?

The issue list of this repo is exclusively for bug reports and feature requests. For simple questions, please use the following resources:
Read the docs: https://vuejs.org/guide/
Look for/ask questions on stack overflow: https://stackoverflow.com/questions/ask?tags=vue.js

Try to search for your issue, it may have already been answered or even fixed in the development branch.
It is required that you clearly describe the steps necessary to reproduce the issue you are running into. Issues with no clear repro steps will not be triaged. If an issue labeled "need repro" receives no further input from the issue author for more than 5 days, it will be closed.
It is recommended that you make a JSFiddle/JSBin/Codepen to demonstrate your issue. You could start with this template that already includes the latest version of Vue.
For potential SSR (Server Side Rendering) issue or bugs that involves build setups, you can create a reproduction repository with steps in the README.
If your issue is resolved but still open, don’t hesitate to close it. In case you found a solution by yourself, it could be helpful to explain how you fixed it.

Remove the template from below and provide thoughtful commentary and code samples on what this feature means for your product. What will it allow you to do that you can't do today? How will it make current work-arounds straightforward? What potential bugs and edge cases does it help to avoid? etc. Please keep it product-centric.

A minimal JSBin, JSFiddle, Codepen, or a GitHub repository that can reproduce the bug.
You could start with this template: https://jsfiddle.net/39epgLj0/

surmon-china / vue-codemirror