Q1a: Why are you not providing the value when you call selectedItems.set in your Map practical example?
Q1b: Since you are not providing the value, could you simply use an array or Set of strings in your Map practical example? If you need helper methods, Set does have add and delete.
Q2: When you talk about performances of object deletion vs map entry deletion, you do not provide figures or references. Could you elaborate more on it please? I can't imagine why deleting a key from an object will have performance issue.
Update:
I see your conversation with LUKESHIRU and I think you use Map over an array or Set mainly because of performance ("scalability") as the Map implementation in V8 is a hash map. I think you should include this in your article stressing that performance is a huge consideration (at least in your practical example) because "why not an array or Set" may be the first thing people think of when they read your Map practical example. Otherwise, it is a great article!!
However, it will only be an issue when you have tons of records inside the array or Set of selected items I guess (I did not test it) when you navigate between the rightmost pages or pages without selection and it does lookups in O(N) multiple times. In this case, without using a Map, I think we can have an array of array/Set of strings, where the first layer of array is the page number and the second layer is the selected items on that page. I think it should perform pretty well, but to obtain a flat list of strings, we will need to flat map the array.
Thanks @blackr1234
, yup i will try and include the performance specific point as well.
Whenever i have to render items and want to do a lookup to a variable to get an idea about what states need to render, i usually start with using array's and then gradually move to either objects or maps depending upon the use-case(this always happens post profiling session).
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May I ask some questions which may seem silly:
Q1a: Why are you not providing the value when you call
selectedItems.setin yourMappractical example?Q1b: Since you are not providing the value, could you simply use an array or
Setof strings in yourMappractical example? If you need helper methods,Setdoes haveaddanddelete.Q2: When you talk about performances of object deletion vs map entry deletion, you do not provide figures or references. Could you elaborate more on it please? I can't imagine why deleting a key from an object will have performance issue.
Update:
I see your conversation with LUKESHIRU and I think you use
Mapover an array orSetmainly because of performance ("scalability") as theMapimplementation in V8 is a hash map. I think you should include this in your article stressing that performance is a huge consideration (at least in your practical example) because "why not an array orSet" may be the first thing people think of when they read yourMappractical example. Otherwise, it is a great article!!However, it will only be an issue when you have tons of records inside the array or
Setof selected items I guess (I did not test it) when you navigate between the rightmost pages or pages without selection and it does lookups in O(N) multiple times. In this case, without using aMap, I think we can have an array of array/Setof strings, where the first layer of array is the page number and the second layer is the selected items on that page. I think it should perform pretty well, but to obtain a flat list of strings, we will need to flat map the array.Thanks @blackr1234 , yup i will try and include the performance specific point as well.
Whenever i have to render items and want to do a lookup to a variable to get an idea about what states need to render, i usually start with using array's and then gradually move to either objects or maps depending upon the use-case(this always happens post profiling session).