JavaScript Fundamentals: Reference VS Copy

[@singhkr]

last concept of deep clone is truly awesome

[@franciscalizo7600]

Any reason why at 5:45, array.map() method isn't used when using the other ES6 methods?

[@djvesko]

Great lesson for JS newbies and great reminder for me.

[@ZarateAdriel]

the copy / assignation in arrays and objects that doesn't happen in strings and number, is about mutability ?

[@ZarateAdriel]

What about for in? I just note that isn't a deep object copy, but works well for arrays

[@bokisa007]

very useful, just wanted to add that when using Object.assign, one can add desired properties directly inside of its first param, instead of making it an empty obj and using 3rd to add params. For example: Object.assign({}, wes, {age:26}) can be done like this: Object.assign({age:26}, wes)

[@cagmz]

Using an empty object for the first param is the correct approach. The way I think of Object.assign is that it does a left-to-right composition of objects. That is, it when called with an empty object as the first param, it merges the `wes` object into the empty object producing a temporary object, and then it merges { age: 26 } into that object. If you use the "desired properties" as the first param, any matching properties from the second param will overwrite those in the first param. Example: > const wes = { age: 27 }; undefined > wes {age: 27} > Object.assign({age:26}, wes) {age: 27} // expected 26

[@ericmcgrath2514]

Welcome back Wes

[@WesBos]

thanks!

[@Suneriins234]

Thanks.I learn so many things.

All those methods of copying arrays make shallow copies. For example: let ar1 = [1,2,3,['a','b','c'],5,6]; let ar2 = ar1.slice(); ar2[3][1] = "BOO!" console.log(ar1); // :( In order to make deep copies, one needs to make a recursive function, for example: function copyArray(arr) { let copy; if (null == arr || "object" != typeof arr) return arr; if (arr instanceof Array) { copy = []; for (const item of arr) { copy.push(copyArray(item)); } return copy; } throw new Error("Unexpected data type"); }

[@mriduljain1981]

bro would be happy to know that object spread do exists now

[@kisanb]

Wes, const cap3 ={...person}; worked for me...

[@WesBos]

It's in Chrome now!

[@rammyramkumar]

What is the editor and font you use ?

[@WesBos]

Yuuup

[@hibritusta2642]

Thanks

[@ClevertonHeusner]

It's insane.

[@furqanashraf5638]

how bout new keyword

[@forgettd]

Poppy and Lux. Hm...

[@kissu_io]

DEMACIA !

[@animeshsingh4290]

Deep Clone function if anyone needs it function cloneObject(obj) { var clone = {}; for(var i in obj) { if(obj[i] != null && typeof(obj[i])=="object") clone[i] = cloneObject(obj[i]); else clone[i] = obj[i]; } return clone; }

[@Ludo045]

thanks god, now we have spread, haha.