for statement with index and value

Tingan Ho tingan87 at gmail.com
Tue Jul 14 02:13:26 UTC 2015


Just following a discussion we had on TypeScript
https://github.com/Microsoft/TypeScript/issues/3835

In most times, I just need the value in an array, so I use a for..of loop.
But then, I find out that I need the index too, then I need to rewrite my
whole for loop expression. Happens all the time for me.

I have to ask why there doesn't exist a `for statement` where I can get the
index and value of an array directly? Or for that matter property and value
of an object?

`.forEach` is not ideal since you can't break, break to outer loop and
continue cleanly. Even though you can achieve this with other array
methods, I don't think they are as productive as a for-statement.

What I'm suggesting is augmenting the current syntax for `for..of` loops.
And support an overloading pattern so that we don't need to rewrite the
whole for loop expression to just to get the index when we already getting
the value.

```
// overloads
for (let value, index of values) { ... }
for (let value of values) { ... }
```

PS. Sorry if this has already discussed. Couldn't find any on Google and
the esdiscuss.org page doesn't have any search capabilities.
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