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@_cha1tanya
Rescuing a SPAghetti
React project
Prathamesh Sonpatki
Last9
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Build mode
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Reality sinks in
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Bad code
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Bad code
• Hard to extend
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Bad code
• Hard to extend
• Duplication
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Bad code
• Hard to understand
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Bad code
• Hard to understand
• Lacks consistency
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Bad code
• Hard to understand
• Lacks consistency
• Cascading failures
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Bad code to Good code
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Bad code to Good code
Confidence Safety
Shared mental model
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Confidence
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Doing one thing well
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function validateTimestamp(atTimestamp) {
if (atTimestamp > 0) {
return true;
}
return false;
}
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function validateTimestamp(atTimestamp) {
if (atTimestamp > 0) {
dispatch();
return true;
}
return false;
}
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function validateTimestamp(atTimestamp, currentUser) {
if (atTimestamp > 0) {
if (currentUser.admin) {
dispatch()
}
return true;
}
return false;
}
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function validateTimestamp(atTimestamp) {
if (atTimestamp > 0) {
return true;
}
return false;
}
validTs = validateTimestamp(atTimestamp);
if (validTs && currentUser.admin) {
dispatch()
}
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Tests
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Cypress
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Hooks
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function useDidUpdateEffect(fn, inputs) {
const fncRef = useRef();
fncRef.current = fn;
const didMountRef = useRef(false);
useEffect(() => {
if (!didMountRef.current) {
didMountRef.current = true;
} else {
return fncRef.current();
}
// eslint-disable-next-line react-hooks/exhaustive-deps
}, inputs);
}
useDidUpdateEffect
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useCallback
true === true // true
false === false // true
1 === 1 // true
'a' === 'a' // true
{} === {} // false
[] === [] // false
() => {} === () => {} // false
const z = {}
z === z // true
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useCallback
const isSelected = useCallback((item) => selectedItems.includes(item), [selectedItems]);
return (
{listItems.map((item) => (
onSelect(item)}
disableGutters
classes={{ root: classes.listItemRoot, selected: classes.listItemSelected }}
selected={isSelected(item)}
button
>
{item}
))}
);
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react-hooks/exhaustive-deps
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useEffect(() => {
if (graphType === GraphType.Custom && views.length === 0) {
setSelectedNodeIdents([]);
}
}, [views.length]);
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useEffect(() => {
if (graphType === GraphType.Custom && views.length === 0) {
setSelectedNodeIdents([]);
}
}, [views.length, graphType]);
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Safety Toolkit
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TypeScript
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export type Timestamp = number;
export type MaybeTimestamp = Timestamp| null | undefined;
export interface TimeRange {
from: Timestamp;
to: Timestamp;
}
export enum ViewType {
Custom = 'custom',
Automatic = 'automatic',
}
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function validateTimestamp(atTimestamp: Timestamp): boolean {
....
}
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export interface Query {
where?: { name: string };
select?: { type: 'custom' | ‘automatic' };
}
export interface QueryWithLimit extends Query {
limit: number;
}
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Code reusability
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No surprises
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ESLint & Prettier
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eslint --fix --ext .js,.jsx,.ts,.tsx src --color --max-warnings 0
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Shared mental model
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knowledge structure(s) held by each member of a team
that enables them to form accurate explanations and expectations
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Sequence diagrams
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Flowcharts
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Comments
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Bad code to Good code
Confidence Safety
Shared mental model
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Thank you!
last9.io
prathamesh.tech