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

How to use

Command line

$ npm install -g es-checker
$ es-checker

Node.js

First install es-checker locally.

$ npm install --save es-checker

Then require it in your script.

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

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

The whole Api List please see below.

Browser

First insert es-checker.js into your page.

<script src="http://ruanyf.github.io/es-checker/es-checker.js"></script>

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

<script>
if (Supports.letConst) {
  let x = 5;
} else {
  var x = 5;
}
</script>

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