typeforce

Another biased type checking solution for Javascript.

Exception messages may change between patch versions, as often the patch will change some behaviour that was unexpected and naturally it results in a different error message.

Examples

consttypeforce=require('typeforce')// supported primitives 'Array', 'Boolean', 'Buffer', 'Number', 'Object', 'String'typeforce('Array',[])typeforce('Number',[])// TypeError: Expected Number, got Array// array typestypeforce(['Object'],[{}])typeforce(typeforce.arrayOf('Object'),[{},{},{}])// enforces object properties typeforce({foo: 'Number'},{foo: 'bar'})// TypeError: Expected property "foo" of type Number, got String "bar"// maybe typestypeforce('?Number',2)typeforce('?Number',null)typeforce(typeforce.maybe(typeforce.Number),2)typeforce(typeforce.maybe(typeforce.Number),null)// sum typestypeforce(typeforce.anyOf('String','Number'),2)typeforce(typeforce.allOf({x: typeforce.Number},{y: typeforce.Number}),{x: 1,y: 2})// value typestypeforce(typeforce.value(3.14),3.14)// custom typesfunctionLongString(value,strict){if(!typeforce.String(value))returnfalseif(value.length!==32)returnfalsereturntrue}typeforce(LongString,'00000000000000000000000000000000')// => OK!typeforce(LongString,'not long enough')// TypeError: Expected LongString, got String 'not long enough'

Protips:

// use precompiled primitives for high performancetypeforce(typeforce.Array,array)// or just precompile a templateconsttype={foo: 'Number',bar: '?String'}constfastType=typeforce.compile(type)// fastType => typeforce.object({// foo: typeforce.Number,// bar: typeforce.maybe(typeforce.String)// })// use strictness for recursive types to enforce whitelisting propertiestypeforce({x: 'Number'},{x: 1},true)// OK!typeforce({x: 'Number'},{x: 1,y: 2},true)// TypeError: Unexpected property 'y' of type Number

Protips (extended types):

typeforce(typeforce.tuple('String','Number'),['foo',1])// OK!typeforce(typeforce.tuple('Number','Number'),['not a number',1])// TypeError: Expected property "0" of type Number, got String 'not a number'typeforce(typeforce.map('Number'),{'anyKeyIsOK': 1})// OK!typeforce(typeforce.map('Number',typeforce.HexN(8)),{'deadbeef': 1,'ffff0000': 2})// OK!functionFoo(){this.x=2}typeforce(typeforce.quacksLike('Foo'),newFoo())// OK!// Note, any Foo will dotypeforce(typeforce.quacksLike('Foo'),new(functionFoo(){}))// OK!

Protips (no throw)

consttypeforce=require('typeforce/nothrow')constvalue='foobar'if(typeforce(typeforce.Number,value)){// didn't throw!console.log(`${value} is a number`)// never happens}else{console.log(`Oops, ${typeforce.error.message}`)// prints 'Oops, Expected Number, got String foobar'}

Protips (async)

consttypeforce=require('typeforce/async')typeforce(typeforce.Number,value,function(err){if(err)returnconsole.log(`Oops, ${typeforce.error.message}`)console.log(`${value} is a number`)// never happens})

WARNING: Be very wary of using the quacksLike type, as it relies on the Foo.name property. If that property is mangled by a transpiler, such as uglifyjs, you will have a bad time.

LICENSE MIT