function f(a, opts) {
let b = opts && 'b' in opts ? opts.b : null;
let c = opts && 'c' in opts ? opts.c : c_default;
...
After:
function f(a, {b = null, c = c_default} = {}) {
...
Note:
- Still reverting to old code when any parameter clashes with reserved JS names (see discussion in https://github.com/dart-lang/dev_compiler/issues/392)
- When a parameter clashes with a Object.prototype property, using a clean default opts value (Object.create(null)).
- Passing opts through in aliased constructors, both for speed/concision and correctness (since default param value semantic is weird there)
BUG=
R=jmesserly@google.com
Review URL: https://codereview.chromium.org/1484263002 .
Olivier Chafik
07d3998cdc