Created
June 29, 2017 16:20
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/* eslint-disable no-console */ | |
import _ from 'lodash'; | |
// Drop this into a component that wastes time according to Perf.printWasted() | |
// to find out what state/props should be preserved. Once it says "Update | |
// avoidable!" for {state, props}, you should be able to drop in | |
// React.addons.PureRenderMixin or React.PureComponent. | |
// | |
// From: http://benchling.engineering/deep-dive-react-perf-debugging/ | |
// | |
// Usage: | |
// | |
// componentDidUpdate(prevProps, prevState) { | |
// whyDidYouUpdate.call(this, prevProps, prevState); | |
// } | |
function isRequiredUpdateObject(o) { | |
return Array.isArray(o) || (o && o.constructor === Object.prototype.constructor); | |
} | |
function deepDiff(o1, o2, p) { | |
const notify = (status) => { | |
console.warn('Update %s', status); | |
console.log('%cbefore', 'font-weight: bold', o1); | |
console.log('%cafter ', 'font-weight: bold', o2); | |
}; | |
if (!_.isEqual(o1, o2)) { | |
console.group(p); | |
if ([o1, o2].every(_.isFunction)) { | |
notify('avoidable?'); | |
} else if (![o1, o2].every(isRequiredUpdateObject)) { | |
notify('required.'); | |
} else { | |
const keys = _.union(_.keys(o1), _.keys(o2)); | |
for (const key of keys) { | |
deepDiff(o1[key], o2[key], key); | |
} | |
} | |
console.groupEnd(); | |
} else if (o1 !== o2) { | |
console.group(p); | |
notify('avoidable!'); | |
if (_.isObject(o1) && _.isObject(o2)) { | |
const keys = _.union(_.keys(o1), _.keys(o2)); | |
for (const key of keys) { | |
deepDiff(o1[key], o2[key], key); | |
} | |
} | |
console.groupEnd(); | |
} | |
} | |
function whyDidYouUpdate(prevProps, prevState) { | |
deepDiff({ props: prevProps, state: prevState }, | |
{ props: this.props, state: this.state }, | |
this.constructor.displayName); | |
} | |
export default whyDidYouUpdate; |
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