Visualforce

If you are using ts-force in an application running in VisualForce, obtaining an access token is simple:

app.page

<apex:page showHeader="true" sidebar="false" standardStylesheets="false" docType="html-5.0">
    <script type="text/javascript">
        //rest details
        const __ACCESSTOKEN__ = '{!JSENCODE($Api.Session_ID})';
        const __RESTHOST__ = '{!JSENCODE(URLFOR("/", null)})';
    </script>
    <div id="root"></div>
</apex:page>

index.ts

// globals set via VF page
declare let __RESTHOST__: string;
declare let __ACCESSTOKEN__: string;

setDefaultConfig({
    accessToken: __ACCESSTOKEN__,
    instanceUrl: __RESTHOST__,
});

In order to make certain API request, you may need to add a CORS Allowlist entry for the VisualForce domain.