On 17 April 2015 at 14:17, Mathias Bynens <[email protected]> wrote:
> On Fri, Apr 17, 2015 at 7:53 AM, Glen Huang <[email protected]> wrote: > > I've completely replaced "var" with "let" in my es 2015 code, but I > noticed most variables I introduced never change. > > Note that `const` has nothing to do with the value of a variable > changing or not. It can still change: > > const foo = {}; > foo.bar = 42; // does not throw > > `const` indicates the *binding* is constant, i.e. there will be no > reassignments etc. > I have to nitpick on this. In usual nomenclature of programming language semantics the "value" in question is the _reference_ to the object (for types with reference semantics), and that does not change. That the object itself actually can be mutable is a separate property. The idea that const somehow applies transitively is a specific idiosyncrasy of low-level languages like C and friends, that make flattening and copying of mutable objects an implicit part of their semantics. It is not the norm, and actually rather contorted semantically. /Andreas > In my post-ES6 code, I use `const` by default, falling back to `let` > if I explicitly need rebinding. `var` is for legacy code. > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss >
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