Define namespaceResolver in TypeScript

Question

I can't figure out how to define properly the namespaceResolver function in TypeScript. I have the following resolver function:

(prefix: string): string => {
    if (prefix === "wms") {
        return "http://www.opengis.net/wms";
    } else {
        return null;
    }

But the compiler complains that:

TS2345: Argument of type '(prefix: string) => string' is not assignable to parameter of type 'XPathNSResolver'. Property 'lookupNamespaceURI' is missing in type '(prefix: string) => string'.

If I check the implementation in lib.dom.d.ts, the lookupNaemspaceURI's return value is string too. So I have no idea how should I fix this.

lib.dom.d.ts:

interface XPathNSResolver {
    lookupNamespaceURI(prefix: string): string;
}

EDIT

Here is the whole code:

doc.evaluate("/wms:WMS_Capabilities/wms:Service/wms:Name", doc, (prefix: string): string => {
                    if (prefix === "wms") {
                        return "http://www.opengis.net/wms";
                    } else {
                        return null;
                    }
                }, XPathResult.STRING_TYPE, null);

Runtime Terror · Accepted Answer · 2018-04-16 05:20:39Z

1

Ok, so I figured it out.

I created an XPathNSReslover first:

private xpathResolver: XPathNSResolver = {
        lookupNamespaceURI: prefix => {
            if (prefix === "wms") {
                return "http://www.opengis.net/wms";
            } else {
                return null;
            }
        }
    };

Then I just use this xpathResolver in my evaluate method implementation:

doc.evaluate("/wms:WMS_Capabilities/wms:Service/wms:Name", doc, this.xpathResolver, XPathResult.STRING_TYPE, null);

answered Apr 16, 2018 at 5:20

Runtime Terror

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Comments

Jade Mathre · Accepted Answer · 2022-10-05 17:49:50Z

0

For anyone who encounters this issue, I would recommend using 'xpath-ts' instead of 'xpath'. With xpath-ts, convoluted typing (such as in the other solution) can be avoided.

answered Oct 5, 2022 at 17:49

Jade Mathre

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