1st javascript task#4
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| function groupByKey(array, key) { | ||
| return array.reduce((hash, obj) => { | ||
| if(obj[key] === undefined) return hash; | ||
| return Object.assign(hash, { [obj[key]]:( hash[obj[key]] || [] ).concat(obj)}) |
| @@ -0,0 +1,18 @@ | |||
| function groupByKey(array, key) { | |||
| return array.reduce((hash, obj) => { | |||
| if(obj[key] === undefined) return hash; | |||
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has key function or anything like this?
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| function GroupByKey(array,key) | |||
| { | |||
| var tempData = {}; | |||
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Please don't use var (only use if its extremely necessary to do so.)
| {id:4,name:"Rehan", city:"Lahore"}, | ||
| {id:5,name:"Saqib", city:"Karachi"}, | ||
| {id:6,name:"Farhan", city:"Islamabad"} | ||
| ]; |
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Use prettier with your VS Code
| {id:6,name:"Farhan", city:"Islamabad"} | ||
| ]; | ||
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| let key='city'; |
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should be const instead off let
| { | ||
| var tempData = {}; | ||
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| for ( var index=0; index<array.length; index++ ) |
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The logic works fine and is good.
But I want you to write another function that uses array.reduce method to do the same thing.
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| function GroupByKey(array,key) | |||
| { | |||
| tempData = {}; | |||
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never declare a variable without using let or const.
Use const here as the object reference is never changed later on.
| tempData[array[index][key]]=[]; | ||
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| } | ||
| tempData[array[index][key]].push(array[index]) |
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array[index][key] this is used twice in the for loop so the sensible thing would be to assign it to a variable and then use it at both places. So later on if we need to make a change, we only need to make in 1 place.
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Ok Sir Let me resolve it
| const key='city'; | ||
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| function GroupByKey(arr,key) { | ||
| const tempData=arr.reduce((acc,cv)=>{ |
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Do we really have to create this tempData variable?
| const key='city'; | ||
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| function GroupByKey(arr,key) { | ||
| const tempData=arr.reduce((acc,cv)=>{ |
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When you take parameters make sure they are descriptive. I can't understand much by looking at this 'cv' variable.
| function GroupByKey(arr,key) { | ||
| const tempData=arr.reduce((acc,cv)=>{ | ||
| if(!acc[cv[key]]){ | ||
| acc[cv[key]]=[] |
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Rehan bhai mentioned this before acc[cv[key]] can be stored as a variable because you are using it in more than on place
| acc[cv[key]]=[] | ||
| } | ||
| acc[cv[key]].push(cv) | ||
| tempobj=acc |
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i cannot see the declaration of this tempObj where is this declared
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