What is the use case for var in ES6?

Question

If the let keyword introduces a proper implementation of block scope, does var any longer have a use case? I am looking at this from a software des

Answer 1

Practically there are some use-cases I found for myself.

Sometimes you may want to declare variable in try-catch like so:

try {
    //inits/checks code etc
    let id = getId(obj);

    var result = getResult(id);
} catch (e) {
    handleException(e);
}

//use `result`

With let the result declaration would be before try, which is a bit early and out of context for the author and a reader of the code.

Same is for conditional declarations:

if (opts.re) {
    var re = new RegExp(opts.re);
    var result = match(re);
    if (!result) return false;
}

//use result here safely

With let this code would be a bit forced to complain "good style", though that might be impractical.

Also I can imagine the case where you would like to use variables belonging to the loop block:

for (var x = 0; x < data.width; x++) {
    if (data[x] == null) break;
    //some drawing/other code
}

//here we have the `x` pointing to the end of data

Someone with high beauty standards may consider that untidy, I myself prefer lets, but if the code I edit already contains vars - that is natural to use them and makes coding easier.