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owl/doc/reference/utils.md
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Géry Debongnie 1fe0bf08b1 [IMP] misc: export the validate function
The props validation code is actually quite difficult to get right.
Also, it is sometimes useful to be able to validate an object against a
specified schema. Therefore, this commit exports the standalone validate
function as an utility function.
2022-05-24 13:52:42 +02:00

81 lines
1.9 KiB
Markdown

# 🦉 Utils 🦉
Owl export a few useful utility functions, to help with common issues. Those
functions are all available in the `owl.utils` namespace.
## Content
- [`whenReady`](#whenready): executing code when DOM is ready
- [`loadFile`](#loadfile): loading a file (useful for templates)
- [`EventBus`](#eventbus): a simple EventBus
- [`validate`](#validate): a validation function
## `whenReady`
The function `whenReady` returns a `Promise` resolved when the DOM is ready (if
not ready yet, resolved directly otherwise). If called with a callback as
argument, it executes it as soon as the DOM ready (or directly).
```js
const { whenReady } = owl;
await whenReady();
// do something
```
or alternatively:
```js
whenReady(function () {
// do something
});
```
## `loadFile`
`loadFile` is a helper function to fetch a file. It simply
performs a `GET` request and returns the resulting string in a promise. The
initial usecase for this function is to load a template file. For example:
```js
const { loadFile } = owl;
async function makeEnv() {
const templates = await loadFile("templates.xml");
// do something
}
```
## `EventBus`
It is a simple `EventBus`, with the same API as usual DOM elements, and an
additional `trigger` method to dispatch events:
```js
const bus = new EventBus();
bus.addEventListener("event", () => console.log("something happened"));
bus.trigger("event"); // 'something happened' is logged
```
## `validate`
The `validate` function is a function that validates if a given object satisfies a
specified schema. It is actually used by Owl itself to perform
[props validation](props.md#props-validation). For example:
```js
validate(
{ a: "hey" },
{
id: Number,
url: [Boolean, { type: Array, element: Number }],
}
);
// throws an error with the following information:
// - unknown key 'a',
// - 'id' is missing (should be a number),
// - 'url' is missing (should be a boolean or list of numbers),
```