github/puppeteer
0
0
Fork 0
mirror of https://github.com/puppeteer/puppeteer synced 2024-06-14 14:02:48 +00:00
Code Issues Packages Projects Releases Wiki Activity

chore: format docs (#8629)

Browse Source
This commit is contained in:
jrandolf
2022-07-05 15:41:43 +02:00
committed by GitHub
parent 9e596d0761
commit b5a345b06b
726 changed files with 17463 additions and 15301 deletions
Download Patch File Download Diff File Expand all files Collapse all files

151
docs/api/puppeteer.page.__eval.md
View File

@@ -1,71 +1,80 @@
---
sidebar_label: Page.$$eval
---
# Page.$$eval() method
This method runs `Array.from(document.querySelectorAll(selector))` within the page and passes the result as the first argument to the `pageFunction`.
**Signature:**
```typescript
class Page {$$eval<Selector extends keyof HTMLElementTagNameMap, Params extends unknown[], Func extends EvaluateFunc<[
HTMLElementTagNameMap[Selector][],
...Params
]> = EvaluateFunc<[HTMLElementTagNameMap[Selector][], ...Params]>>(selector: Selector, pageFunction: Func | string, ...args: Params): Promise<Awaited<ReturnType<Func>>>;}
```
## Parameters
| Parameter | Type | Description |
| --- | --- | --- |
| selector | Selector | the [selector](https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Selectors) to query for |
| pageFunction | Func \| string | the function to be evaluated in the page context. Will be passed the result of <code>Array.from(document.querySelectorAll(selector))</code> as its first argument. |
| args | Params | any additional arguments to pass through to <code>pageFunction</code>. |
**Returns:**
Promise&lt;Awaited&lt;ReturnType&lt;Func&gt;&gt;&gt;
The result of calling `pageFunction`. If it returns an element it is wrapped in an [ElementHandle](./puppeteer.elementhandle.md), else the raw value itself is returned.
## Remarks
If `pageFunction` returns a promise `$$eval` will wait for the promise to resolve and then return its value.
## Example 1
```ts
// get the amount of divs on the page
const divCount = await page.$$eval('div', divs => divs.length);
// get the text content of all the `.options` elements:
const options = await page.$$eval('div > span.options', options => {
return options.map(option => option.textContent)
});
```
If you are using TypeScript, you may have to provide an explicit type to the first argument of the `pageFunction`. By default it is typed as `Element[]`, but you may need to provide a more specific sub-type:
## Example 2
```ts
// if you don't provide HTMLInputElement here, TS will error
// as `value` is not on `Element`
await page.$$eval('input', (elements: HTMLInputElement[]) => {
return elements.map(e => e.value);
});
```
The compiler should be able to infer the return type from the `pageFunction` you provide. If it is unable to, you can use the generic type to tell the compiler what return type you expect from `$$eval`:
## Example 3
```ts
// The compiler can infer the return type in this case, but if it can't
// or if you want to be more explicit, provide it as the generic type.
const allInputValues = await page.$$eval<string[]>(
'input', (elements: HTMLInputElement[]) => elements.map(e => e.textContent)
);
```
---
sidebar_label: Page.$$eval
---
# Page.$$eval() method
This method runs `Array.from(document.querySelectorAll(selector))` within the page and passes the result as the first argument to the `pageFunction`.
**Signature:**
```typescript
class Page {
$$eval<
Selector extends keyof HTMLElementTagNameMap,
Params extends unknown[],
Func extends EvaluateFunc<
[HTMLElementTagNameMap[Selector][], ...Params]
> = EvaluateFunc<[HTMLElementTagNameMap[Selector][], ...Params]>
>(
selector: Selector,
pageFunction: Func | string,
...args: Params
): Promise<Awaited<ReturnType<Func>>>;
}
```
## Parameters
| Parameter | Type | Description |
| ------------ | -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| selector | Selector | the [selector](https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Selectors) to query for |
| pageFunction | Func \| string | the function to be evaluated in the page context. Will be passed the result of <code>Array.from(document.querySelectorAll(selector))</code> as its first argument. |
| args | Params | any additional arguments to pass through to <code>pageFunction</code>. |
**Returns:**
Promise&lt;Awaited&lt;ReturnType&lt;Func&gt;&gt;&gt;
The result of calling `pageFunction`. If it returns an element it is wrapped in an [ElementHandle](./puppeteer.elementhandle.md), else the raw value itself is returned.
## Remarks
If `pageFunction` returns a promise `$$eval` will wait for the promise to resolve and then return its value.
## Example 1
```ts
// get the amount of divs on the page
const divCount = await page.$$eval('div', divs => divs.length);
// get the text content of all the `.options` elements:
const options = await page.$$eval('div > span.options', options => {
return options.map(option => option.textContent);
});
```
If you are using TypeScript, you may have to provide an explicit type to the first argument of the `pageFunction`. By default it is typed as `Element[]`, but you may need to provide a more specific sub-type:
## Example 2
```ts
// if you don't provide HTMLInputElement here, TS will error
// as `value` is not on `Element`
await page.$$eval('input', (elements: HTMLInputElement[]) => {
return elements.map(e => e.value);
});
```
The compiler should be able to infer the return type from the `pageFunction` you provide. If it is unable to, you can use the generic type to tell the compiler what return type you expect from `$$eval`:
## Example 3
```ts
// The compiler can infer the return type in this case, but if it can't
// or if you want to be more explicit, provide it as the generic type.
const allInputValues = await page.$$eval<string[]>(
'input',
(elements: HTMLInputElement[]) => elements.map(e => e.textContent)
);
```