{"@attributes":{"version":"2.0"},"channel":{"title":"DEV Community: Baba","description":"The latest articles on DEV Community by Baba (@iskndrvbksh).","link":"https:\/\/dev.to\/iskndrvbksh","image":{"url":"https:\/\/media2.dev.to\/dynamic\/image\/width=90,height=90,fit=cover,gravity=auto,format=auto\/https:%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F58528%2Fb5b846da-3a75-47e1-96fa-17d90d54f3b6.png","title":"DEV Community: Baba","link":"https:\/\/dev.to\/iskndrvbksh"},"language":"en","item":{"title":"What is the purpose of this code?","pubDate":"Mon, 27 Sep 2021 07:54:43 +0000","link":"https:\/\/dev.to\/iskndrvbksh\/what-is-the-purpose-of-this-code-97o","guid":"https:\/\/dev.to\/iskndrvbksh\/what-is-the-purpose-of-this-code-97o","description":"

Today I was playing with the Object.defineProperty<\/code> method and doing weird stuffs like making the 3rd index of an Array<\/code> to \ud83d\udd25always\ud83d\udd25 return 'Frank Stallone' (don't ask why)<\/p>\n\n

console.log([1,2,3,4][3]); \/\/ Frank Stallone<\/code><\/p>\n\n

anyways<\/p>\n\n

I added debugger statement to set method of a descriptor:
\n<\/p>\n\n

\n
Object.defineProperty(Array.prototype, 3, {\n  set() { debugger; }\n});\n<\/code><\/pre>\n\n<\/div>\n\n\n\n
after typing something to the console triggers debugger with 2 calls in the call stack:
\n\"image\"<\/a><\/p>\n\n
Code snippet in the first call:
\n<\/p>\n\n
\n
(<\/span>function<\/span> i<\/span>(<\/span>t<\/span>)<\/span> {<\/span>\n    let<\/span> e<\/span>;<\/span>\n    e<\/span> =<\/span> \"<\/span>string<\/span>\"<\/span> ===<\/span> t<\/span> ?<\/span> new<\/span> String<\/span>(<\/span>\"\"<\/span>)<\/span> :<\/span> \"<\/span>number<\/span>\"<\/span> ===<\/span> t<\/span> ?<\/span> new<\/span> Number<\/span>(<\/span>0<\/span>)<\/span> :<\/span> \"<\/span>bigint<\/span>\"<\/span> ===<\/span> t<\/span> ?<\/span> Object<\/span>(<\/span>BigInt<\/span>(<\/span>0<\/span>))<\/span> :<\/span> \"<\/span>boolean<\/span>\"<\/span> ===<\/span> t<\/span> ?<\/span> new<\/span> Boolean<\/span>(<\/span>!<\/span>1<\/span>)<\/span> :<\/span> this<\/span>;<\/span>\n    const<\/span> s<\/span> =<\/span> [];<\/span>\n    try<\/span> {<\/span>\n        for<\/span> (<\/span>let<\/span> i<\/span> =<\/span> e<\/span>;<\/span> i<\/span>;<\/span> i<\/span> =<\/span> Object<\/span>.<\/span>getPrototypeOf<\/span>(<\/span>i<\/span>))<\/span> {<\/span>\n            if<\/span> ((<\/span>\"<\/span>array<\/span>\"<\/span> ===<\/span> t<\/span> ||<\/span> \"<\/span>typedarray<\/span>\"<\/span> ===<\/span> t<\/span>)<\/span> &&<\/span> i<\/span> ===<\/span> e<\/span> &&<\/span> i<\/span>.<\/span>length<\/span> ><\/span> 9999<\/span>)<\/span>\n                continue<\/span>;<\/span>\n            const<\/span> n<\/span> =<\/span> {<\/span>\n                items<\/span>:<\/span> [],<\/span>\n                title<\/span>:<\/span> void<\/span> 0<\/span>,<\/span>\n                __proto__<\/span>:<\/span> null<\/span>\n            };<\/span>\n            try<\/span> {<\/span>\n                \"<\/span>object<\/span>\"<\/span> ==<\/span> typeof<\/span> i<\/span> &&<\/span> Object<\/span>.<\/span>prototype<\/span>.<\/span>hasOwnProperty<\/span>.<\/span>call<\/span>(<\/span>i<\/span>,<\/span> \"<\/span>constructor<\/span>\"<\/span>)<\/span> &&<\/span> i<\/span>.<\/span>constructor<\/span> &&<\/span> i<\/span>.<\/span>constructor<\/span>.<\/span>name<\/span> &&<\/span> (<\/span>n<\/span>.<\/span>title<\/span> =<\/span> i<\/span>.<\/span>constructor<\/span>.<\/span>name<\/span>)<\/span>\n            }<\/span> catch<\/span> (<\/span>t<\/span>)<\/span> {}<\/span>\n            s<\/span>[<\/span>s<\/span>.<\/span>length<\/span>]<\/span> =<\/span> n<\/span>;<\/span>\n            const<\/span> o<\/span> =<\/span> Object<\/span>.<\/span>getOwnPropertyNames<\/span>(<\/span>i<\/span>)<\/span>\n              ,<\/span> r<\/span> =<\/span> Array<\/span>.<\/span>isArray<\/span>(<\/span>i<\/span>);<\/span>\n            for<\/span> (<\/span>let<\/span> t<\/span> =<\/span> 0<\/span>;<\/span> t<\/span> <<\/span> o<\/span>.<\/span>length<\/span> &&<\/span> n<\/span>.<\/span>items<\/span>.<\/span>length<\/span> <<\/span> 1<\/span>e4<\/span>;<\/span> ++<\/span>t<\/span>)<\/span>\n                r<\/span> &&<\/span> \/^<\/span>[<\/span>0-9<\/span>]<\/span>\/<\/span>.<\/span>test<\/span>(<\/span>o<\/span>[<\/span>t<\/span>])<\/span> ||<\/span> (<\/span>n<\/span>.<\/span>items<\/span>[<\/span>n<\/span>.<\/span>items<\/span>.<\/span>length<\/span>]<\/span> =<\/span> o<\/span>[<\/span>t<\/span>])<\/span>\n        }<\/span>\n    }<\/span> catch<\/span> (<\/span>t<\/span>)<\/span> {}<\/span>\n    return<\/span> s<\/span>\n}<\/span>\n)<\/span>\n<\/code><\/pre>\n\n<\/div>\n\n\n\n
\n  \n  \n  Can someone explain to me what is the purpose of this code? and what it does?\n<\/h2>\n\n","category":["javascript","discuss"]}}}