我是否需要在 javascript/typescript 中为匿名函数指定返回类型？

Question

I have the following function:

    $('td:eq(' + iColumn + ') input', oSettings.oApi._fnGetTrNodes(oSettings))
        .each(function () {
            aData.push(this.value);
         });

In typescript I am getting a message saying:

Error   3   Function declared a non-void return type, but has no return expression  

Why am I getting this message? I can resolve the message by saying "return true". Should I always specify a return type for this?

Answer 1

The signature of .each() in the jquery.d.ts file on the typescript repository is:

each(func: (index: any, elem: Element) => JQuery);

The jQuery documentation says that

We can stop the loop from within the callback function by returning false.

which implies that this jquery.d.ts is wrong.

If you grab an updated version from Boris Yankov's repository , it will become:

each(func: (index: any, elem: Element) => any);

This form will allow you to return anything, or nothing.