クラスへの割り込み処理とProxyとReflect / method-intercept-with-proxy-and-reflect

初投稿です。

Transcript

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4. ΍Ζ͏ͱͨ͜͠ͱ ਆʢϢʔςΟϦςΟʔΫϥεʣ͸ݴͬͨʮΤϥʔ͋Εʯ
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5. Ͳ͏͠Α͏ͱ͔ͨ͠ Ҋ̍ɿ#VTJOFTT
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6. ࣮૷ͯ͠Έͨʢࣦഊฤʣ // ׂΓࠐΈॲཧ͞ΕΔ Utility Ϋϥε class _Util { static greet(name) { console.log(`hello! ${name}!`) } static throwError(...args) { console.log(‘Sample#throwError') // ͜͜ͰΤϥʔ͕ى͜Δ throw new Error(...args) } } // Proxy ʹΘͨ͢ϋϯυϥ const handler = { get(target, name, receiver) { try { interceptor() return target[name] } catch (e) { onError(e) } } } // ͍ͭ͜ΒΛ export export let interceptor // ׂΓࠐΈॲཧ༻ export let onError // Τϥʔϋϯυϥ export const Util = new Proxy(_Util, handler) // ׂΓࠐΈॲཧͷ࣮૷ interceptor = () => { console.log('intercept!') } onError = (e) => { console.log('onError!') console.log(e) } // ࣮ࡍʹݺͼग़͢ Util.greet('haga') Util.throwError('sample error') 6UJM$MBTTKT #VTJOFTT-PHJDKT উͬͨͳʂ ෩࿊ೖͬͯ͘Δ Χϓʔ
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8. ࣮૷ͯ͠Έͨʢࣦഊฤʣ const handler = { get(target, name, receiver) { try { interceptor() return target[name] } catch (e) { onError(e) } } } ݪҼ͸ʜ ϝιουͦͷ··ฦͯ͠·͢΍Μʜ
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9. ࣮૷ͯ͠Έͨʢ੒ޭʁฤʣ const handler = { get(target, name, receiver) { return (...args) => { const apiMethod = Reflect.get(target, name, receiver) const boundApiMethod = apiMethod.bind(target) try { interceptor() return boundApiMethod(...args) } catch (e) { onError(e) } } } } const handler = { get(target, name, receiver) { try { interceptor() return target[name] } catch (e) { onError(e) } } } 3FqFDUHFU
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11. ࣮૷ͯ͠Έͨʢ੒ޭฤʣ const handler = { get(target, name, receiver) { return (...args) => { try { interceptor() return target[name](...args) } catch (e) { onError(e) } } } } ಈ͍ͨΑʜ
 ʢमਖ਼ͷϓϧϦΫग़͞ͳ͖Όʜʣ ૲ Χϓʔ
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13. ͝੩ௌ͋Γ͕ͱ͏͍͟͝·ͨ͠ Χϓʔʂ