Advise against multiple assignment in var declaration

[hkdobrev]

I'd suggest to include a section in the guide explaining the scoping problems of this:

function foo() {
    var a = b = c = 1;
}

and to advise against it.

See http://stackoverflow.com/questions/1758576/multiple-left-hand-assignment-with-javascript

[justjake]

Submit a PR!

[alexreardon]

Is this redundant given that the var keyword is discouraged? https://github.com/airbnb/javascript/tree/es6#references

[ljharb]

@alexreardon no, you can still do const a = b = c = 3;

[butterthebuddha]

I'd like to take this on!

[ljharb]

@awesomeaniruddh thanks, that'd be great! Since we now basically forbid var in its entirety, we should focus this guide section on const and let, and make sure to link to the relevant eslint rule.

[butterthebuddha]

@ljharb There doesn't appear to be a relevant eslint rule.

[ljharb]

@awesomeaniruddh I believe http://eslint.org/docs/rules/one-var with the option "never" is the one I'm thinking of - we enable that here

[butterthebuddha]

@ljharb Ah, my bad. I didn't notice that the rule works for this particular situation too. PR incoming ASAP!