132 lines
3.4 KiB
TypeScript
132 lines
3.4 KiB
TypeScript
/**
|
|
* External dependencies
|
|
*/
|
|
import { isString } from '@woocommerce/types';
|
|
|
|
interface lazyLoadScriptParams {
|
|
handle: string;
|
|
src: string;
|
|
version?: string;
|
|
after?: string;
|
|
before?: string;
|
|
translations?: string;
|
|
}
|
|
|
|
interface appendScriptAttributesParam {
|
|
id: string;
|
|
innerHTML?: string;
|
|
onerror?: OnErrorEventHandlerNonNull;
|
|
onload?: () => void;
|
|
src?: string;
|
|
}
|
|
|
|
/**
|
|
* In WP, registered scripts are loaded into the page with an element like this:
|
|
* `<script src='...' id='[SCRIPT_ID]'></script>`
|
|
* This function checks whether an element matching that selector exists.
|
|
* Useful to know if a script has already been appended to the page.
|
|
*/
|
|
const isScriptTagInDOM = ( scriptId: string ): boolean => {
|
|
const scriptElements = document.querySelectorAll( `script#${ scriptId }` );
|
|
return scriptElements.length > 0;
|
|
};
|
|
|
|
/**
|
|
* Appends a script element to the document body if a script with the same id
|
|
* doesn't exist.
|
|
*/
|
|
const appendScript = ( attributes: appendScriptAttributesParam ): void => {
|
|
// Abort if id is not valid or a script with the same id exists.
|
|
if ( ! isString( attributes.id ) || isScriptTagInDOM( attributes.id ) ) {
|
|
return;
|
|
}
|
|
const scriptElement = document.createElement( 'script' );
|
|
for ( const attr in attributes ) {
|
|
// We could technically be iterating over inherited members here, so
|
|
// if this is the case we should skip it.
|
|
if ( ! attributes.hasOwnProperty( attr ) ) {
|
|
continue;
|
|
}
|
|
const key = attr as keyof appendScriptAttributesParam;
|
|
|
|
// Skip the keys that aren't strings, because TS can't be sure which
|
|
// key in the scriptElement object we're assigning to.
|
|
if ( key === 'onload' || key === 'onerror' ) {
|
|
continue;
|
|
}
|
|
|
|
// This assignment stops TS complaining about the value maybe being
|
|
// undefined following the isString check below.
|
|
const value = attributes[ key ];
|
|
if ( isString( value ) ) {
|
|
scriptElement[ key ] = value;
|
|
}
|
|
}
|
|
|
|
// Now that we've assigned all the strings, we can explicitly assign to the
|
|
// function keys.
|
|
if ( typeof attributes.onload === 'function' ) {
|
|
scriptElement.onload = attributes.onload;
|
|
}
|
|
if ( typeof attributes.onerror === 'function' ) {
|
|
scriptElement.onerror = attributes.onerror;
|
|
}
|
|
document.body.appendChild( scriptElement );
|
|
};
|
|
|
|
/**
|
|
* Appends a `<script>` tag to the document body based on the src and handle
|
|
* parameters. In addition, it appends additional script tags to load the code
|
|
* needed for translations and any before and after inline scripts. See these
|
|
* documentation pages for more information:
|
|
*
|
|
* https://developer.wordpress.org/reference/functions/wp_set_script_translations/
|
|
* https://developer.wordpress.org/reference/functions/wp_add_inline_script/
|
|
*/
|
|
const lazyLoadScript = ( {
|
|
handle,
|
|
src,
|
|
version,
|
|
after,
|
|
before,
|
|
translations,
|
|
}: lazyLoadScriptParams ): Promise< void > => {
|
|
return new Promise( ( resolve, reject ) => {
|
|
if ( isScriptTagInDOM( `${ handle }-js` ) ) {
|
|
resolve();
|
|
}
|
|
|
|
if ( translations ) {
|
|
appendScript( {
|
|
id: `${ handle }-js-translations`,
|
|
innerHTML: translations,
|
|
} );
|
|
}
|
|
if ( before ) {
|
|
appendScript( {
|
|
id: `${ handle }-js-before`,
|
|
innerHTML: before,
|
|
} );
|
|
}
|
|
|
|
const onload = () => {
|
|
if ( after ) {
|
|
appendScript( {
|
|
id: `${ handle }-js-after`,
|
|
innerHTML: after,
|
|
} );
|
|
}
|
|
resolve();
|
|
};
|
|
|
|
appendScript( {
|
|
id: `${ handle }-js`,
|
|
onerror: reject,
|
|
onload,
|
|
src: version ? `${ src }?ver=${ version }` : src,
|
|
} );
|
|
} );
|
|
};
|
|
|
|
export default lazyLoadScript;
|