1.3 KiB
1.3 KiB
Playground
Playground is a proving ground for possible ES7 proposals.
NOTE: These features are in no way endorsed by Ecma International and are not a part of ES6. They might become a part of ECMAScript in the future.
Usage
$ 6to5 --playground
to5.transform("code", { playground: true });
NOTE: Enabling playground also enables experimental support.
Features
Memoization assignment operator
var obj = {};
obj.x ?= 2;
obj.x; // 2
obj = { x: 1 };
obj.x ?= 2;
obj.x; // 1
obj = { x: undefined }
obj.x ?= 2;
obj.x; // undefined
var obj = {};
obj.x ?= 2;
equivalent to:
var obj = {};
if (!Object.prototype.hasOwnProperty.call(obj, "x")) obj.x = 2;
Method binding
var fn = obj:method;
var fn = obj:method("foob");
["foo", "bar"].map(:toUpperCase); // ["FOO", "BAR"]
[1.1234, 23.53245, 3].map(:toFixed(2)); // ["1.12", "23.53", "3.00"]
equivalent to:
var fn = obj.method.bind(obj);
var fn = obj.method.bind(obj, "foob");
["foo", "bar"].map(function (val) { return val.toUpperCase(); });
[1.1234, 23.53245, 3].map(function (val) { return val.toFixed(2); });