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Typed Functions
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| function getType(arg) { | |
| return ({}).toString.call(arg).match(/\s([a-zA-Z]+)/)[1].toLowerCase(); | |
| } | |
| function typeMatch(arg, type) { | |
| if (typeof arg === 'number' && typeof type === 'number' && isNaN(arg) && isNaN(type)) return true; | |
| if ((typeof arg === 'number' && isNaN(arg)) || (typeof type === 'number' && isNaN(type))) return false; | |
| if (getType(arg) === getType(type)) return true; | |
| if (type instanceof Function && arg.constructor === type) return true; | |
| return false; | |
| } | |
| function typedFunction(paramDefs, fn) { | |
| const fnParams = fn.toString().match(/\((.*?)\)/)[1].split(/,\s*/); | |
| return (...args) => { | |
| fnParams.map((param, idx) => { | |
| if (!typeMatch(args[idx], paramDefs[param])) { | |
| throw new Error(`${ param } must be of type ${ paramDefs[param] }`); | |
| } | |
| }); | |
| fn(...args); | |
| }; | |
| } | |
| const asl = typedFunction({ age: Number, sex: String, loc: String }, (age, sex, loc) => { | |
| // Never tell your true age | |
| console.log(`${ age - 5 }, ${ sex }, ${ loc }`); | |
| }); | |
| const test = typedFunction({ x: null, y: undefined, z: NaN }, (x, y, z) => { | |
| console.log('passed'); | |
| }); |
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