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typescriptdocument.evaluate

Use document.evaluate in TypeScript

How can I use document.evaluate in TypeScript? It's not a method of the Document type, so when I try and use it TypeScript generates an error and doesn't let me compile the code.

Is there some way I can add it to the definition of Document or ignore the compile error?

Solution

  • There are several ways to do this. Since interfaces in TypeScript are extensible, you can just add the required method to the Document interface, like so:

    interface Document{
    evaluate(xpathExpression:any, 
        contextNode?:any, 
        namespaceResolver?:any, 
        resultType?:any, 
        result?:any);
}

    Or you could cast the document to any before calling the evaluate method:

    (<any>document).evaluate('...');

    Something along those lines at any rate.