TypeScript and Dictionary Index

TypeScript and Dictionary Index

I define a Interface, then I define a dictionary variables and want to look up the dictionary based on the key.

interface GroupSettingsMethod { (parameters: any) : Promise<string> | void };
const groupSettingsMethods = {
    '/meeting/create': { 'method': changeGroupMeetingCount },
    '/meeting/update': { 'method': getGroupMeetingCount }
};

..snip…
const methodImpl: GroupSettingsMethod = groupSettingsMethods[uriSuffix.toLowerCase()].method || null;
…snip…

It should lookup the different interface based not he uriSuffix. But in my VS code, it shows up
[ts] Element implicitly has an ‘any’ type because  type ….. has no index signature

I checked some articles here
https://basarat.gitbooks.io/typescript/docs/types/index-signatures.html
https://dev.to/kingdaro/indexing-objects-in-typescript-1cgi

Finally, I solve that by change the dictionary definition to
const groupSettingsMethods:{ [index:string] : any } = {
    '/meeting/create': { 'method': changeGroupMeetingCount },
    '/meeting/update': { 'method': getGroupMeetingCount }
};


References:
https://basarat.gitbooks.io/typescript/docs/types/index-signatures.html
https://dev.to/kingdaro/indexing-objects-in-typescript-1cgi