延迟加载
延迟加载可暂停广告的请求和呈现，直到广告接近用户的视口为止，从而提高网页加载速度、减少资源消耗和争用，并提高广告可见率。
在 SRA 中启用延迟加载后，当第一个广告位进入 fetchMarginPercent 参数指定的视口内时，系统会调用该广告和所有其他广告位。
[null,null,[],[],[],null,["# Lazy loading\n============\n\nLazy loading enables pages to load faster, reduces resource consumption and\ncontention, and improves viewability rate by pausing the requesting and\nrendering of ads until they approach the user's viewport.\n\nWith lazy loading in SRA, when the first ad slot comes within the viewport\nspecified by the [`fetchMarginPercent`](//developers.google.com/publisher-tag/reference#googletag.config.LazyLoadConfig.fetchMarginPercent) property,\nthe call for that ad and all other ad slots is made.\n\nSample implementation\n---------------------\n\n[View demo](https://googleads.github.io/google-publisher-tag-samples/lazy-loading/js/demo.html) This sample makes use of library features that are not fully supported when running in an iframe. To view a demo of this sample in a new window, click the **View demo** button above. \n\n### JavaScript\n\nLoading...\n----------\n\nLoading...\n----------\n\n[Improve this sample](https://github.com/googleads/google-publisher-tag-samples/tree/main/dist/lazy-loading/js) [Report an issue](https://github.com/googleads/google-publisher-tag-samples/issues/new?labels=documentation&template=sample-feedback.md&title=Sample+feedback%3A+lazy-loading/js)\n\n### TypeScript\n\nLoading...\n----------\n\nLoading...\n----------\n\n[Improve this sample](https://github.com/googleads/google-publisher-tag-samples/tree/main/dist/lazy-loading/ts) [Report an issue](https://github.com/googleads/google-publisher-tag-samples/issues/new?labels=documentation&template=sample-feedback.md&title=Sample+feedback%3A+lazy-loading/ts)"]]