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addInitScript()
Adds a script which will be evaluated in one of the following scenarios:
- Whenever a page is created in the browserContext or is navigated.
- Whenever a child [frame](<page>) is attached or navigated in any page in the browserContext. In this case, the script is evaluated in the context of the newly attached [frame](<page>).
The script is evaluated after the document is created but before any of its scripts are run. This is useful to amend the JavaScript environment, for example, to override Math.random
.
Example
JavaScript
import { browser } from 'k6/experimental/browser';
import { check } from 'k6';
export const options = {
scenarios: {
browser: {
executor: 'shared-iterations',
options: {
browser: {
type: 'chromium',
},
},
},
},
};
export default async function () {
const browserContext = browser.newContext();
// This will execute and override the existing implementation of Math.random.
browserContext.addInitScript('Math.random = function(){return 0}');
const page = browserContext.newPage();
// In this example we are going to set the content manually, so we first
// navigate to about:blank which will execute the init script, before setting
// the content on the page.
await page.goto('about:blank');
page.setContent(`
<html>
<head></head>
<body>
<div id="random">waiting...</div>
</body>
<script>
document.getElementById('random').textContent = Math.random();
</script>
</html>`);
check(page, {
zero: (p) => p.locator('#random').textContent() == '0',
});
page.close();
}
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