es-checker

ES-Checker is a feature detection library for ECMAScript in node.js and browser. Please visit demo.

How to use

$3

``bash
$ npm install -g es-checker
$ es-checker
`

![](./screenshot.png)

$3

First install es-checker locally.

`bash
$ npm install --save es-checker
`

Then require it in your script.

`javascript
var Supports = require("es-checker");

if (Supports.letConst) {
let x = 5;
} else {
var x = 5;
}
`

The whole Api List please see below.

$3

First insert es-checker.js into your page.

`html

`

Then use Supports to decide which feature to use. Visit demo.

`html

`

The whole API List please see below.

API

This library is derived from es-feature-tests. The following API is copied from it. Visit FeatureTests.io for more information, including how to test a feature by yourself.

- letConst: let and const
- defaultParameter: default function parameter values
- spreadRest: ... operator
- destructuring: destructuring assignments/declarations for arrays and objects
- parameterDestructuring: destructuring for function parameters
- templateString: ..` Template String Literals
- forOf: for (var v of something) { .. }
- arrow: x => x * x
- generator: function *foo() { .. }
- conciseMethodProperty: o = { b() { .. }, a }
- computedProperty: o = { ["a" + "b"]: 42 }
- moduleExport: In modules, export default foo = 42
- moduleImport: In modules, import bar from "foo"
- class: class A extends B { .. }
- numericLiteral: Octal and binary literal forms (0o1, 0b10)
- oldOctalLiteral: Old octal literal invalid now (01)
- symbol: Symbol primitive
- unicodeEscape: Unicode code-point escape form in string literals ('\u{20BB7}')
- unicodeIdentifier: Unicode code-point escape form in identifier names (\u{20BB7} = 42)
- unicodeRegExp: Unicode code-point escape form in regular expressions (/\u{20BB7}/u)
- stickyRegExp: y flag for sticky regular expressions
- letTDZ: TDZ error for too-early access of let or const declarations
- constRedef: Redefinition of const declarations not allowed
- objectProto: __proto__ in object literal definition sets [[Prototype]] link
- objectSuper: super allowed in object methods
- extendNatives: class ABC extends Array { .. }
- tco: Tail-call optimization for function calls and recursion
- symbolImplicitCoercion: Symbols can't be implicitly coerced (Symbol("a") + "")
- functionNameInfernece: Inferences for function name property for anonymous functions
- objectStatics: Static functions added to Object
- arrayStatics: Static functions added to Array
- arrayMethods: Methods added to Array.prototype
- typedArrays: TypedArrays like Uint8Array (technically a web platform feature long before ES6)
- typedArrayStatics: Some Array statics (like from(..)) added to the TypedArray constructors
- typedArrayMethods: Some Array methods (like map(..)) added to the TypedArray prototypes
- stringMethods: Methods added to String.prototype
- numberStatics: Static functions added to Number
- mathStatics: Static functions added to Math
- collections: Collections added (Map, Set, WeakMap, WeakSet)
- proxy: Proxies
- promise: Promises
- reflect: Reflect

Licensed

MIT