# xml
## Install
Note, if you're using `@xmpp/client` or `@xmpp/component`, you don't need to install `@xmpp/xml`.
`npm install @xmpp/xml`
```js
import xml from "@xmpp/xml";
import { xml } from "@xmpp/client";
import { xml } from "@xmpp/component";
```
## Writing
There's 2 methods for writing XML with xmpp.js
### factory
```js
import xml from "@xmpp/xml";
const recipient = "user@example.com";
const days = ["Monday", "Tuesday", "Wednesday"];
const message = xml(
"message",
{ to: recipient },
xml("body", {}, 1 + 2),
xml(
"days",
{},
days.map((day, idx) => xml("day", { idx }, day)),
),
);
```
If the second argument passed to `xml` is a `string` instead of an `object`, it will be set as the `xmlns` attribute.
```js
// both are equivalent
xml("time", "urn:xmpp:time");
xml("time", { xmlns: "urn:xmpp:time" });
```
### JSX
```js
/** @jsx xml */
import xml from "@xmpp/xml";
const recipient = "user@example.com";
const days = ["Monday", "Tuesday"];
const message = (
{1 + 2}
{days.map((day, idx) => (
${day}
))}
);
```
Requires a preprocessor such as [TypeScript](https://www.typescriptlang.org/) or [Babel](http://babeljs.io/) with [@babel/plugin-transform-react-jsx](https://babeljs.io/docs/en/next/babel-plugin-transform-react-jsx.html).
## Reading
### attributes
The `attrs` property is an object that holds xml attributes of the element.
```js
message.attrs.to; // user@example.com
```
### text
Returns the text value of an element
```js
message.getChild("body").text(); // '3'
```
### getChild
Get child element by name.
```js
message.getChild("body").toString(); // '3'
```
### getChildText
Get child element text value.
```js
message.getChildText("body"); // '3'
```
### getChildren
Get children elements by name.
```js
message.getChild("days").getChildren("day"); // [...]
```
Since `getChildren` returns an array, you can use JavaScript array methods such as [filter](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter) and [find](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/find) to build more complex queries.
```js
const days = message.getChild("days").getChildren("day");
// Find Monday element
days.find((day) => day.text() === "Monday");
days.find((day) => day.attrs.idx === 0);
// Find all days after Tuesday
days.filter((day) => day.attrs.idx > 2);
```
### parent
You can get the parent node using the parent property.
```js
console.log(message.getChild("days").parent === message);
```
### root
You can get the root node using the root method.
```js
console.log(message.getChild("days").root() === message);
```
## Editing
### attributes
The `attrs` property is an object that holds xml attributes of the element.
```js
message.attrs.type = "chat";
```
### text
Set the text value of an element
```js
message.getChild("body").text("Hello world");
```
### append
Adds text or element nodes to the last position.
Returns the parent.
```js
message.append(xml("foo"));
message.append("bar");
message.append(days.map((day) => xml("day", {}, day)));
//
// ...
//
// bar
// Monday
// Tuesday
//
```
### prepend
Adds text or element nodes to the first position.
Returns the parent.
```js
message.prepend(xml("foo"));
message.prepend("bar");
message.prepend(days.map((day) => xml("day", {}, day)));
//
// Tuesday
// Monday
// bar
//
// ...
//
```
### remove
Removes a child element.
```js
const body = message.getChild("body");
message.remove(body);
```
## JSON
You can embed JSON anywhere but it is recommended to use appropriate semantic.
```js
/** @jsx xml */
// write
message.append(
{JSON.stringify(days)}
,
);
// read
JSON.parse(
message
.getChild("myevent", "xmpp:example.org")
.getChildText("json", "urn:xmpp:json:0"),
);
```
See also [JSON Containers](https://xmpp.org/extensions/xep-0335.html) and [Simple JSON Messaging](https://xmpp.org/extensions/xep-0432.html).
## Parsing XML strings
`@xmpp/xml` include a function to parse XML strings.
⚠ Use with care. Untrusted input or substitutions can result in invalid XML and side effects.
```js
import { escapeXML, escapeXMLText } from "@xmpp/xml";
import parse from "@xmpp/xml/lib/parse.js";
const ctx = parse("hello world");
ctx.getChildText("body"); // hello world
```
If you must use with untrusted input, escape it with `escapeXML` and `escapeXMLText`.
```js
const message = parse(`
${escapeXMLText(body)}
,
`);
```