Javascript array deduplication, javascript Array

Javascript array deduplication, javascript Array

// Remove the Array of numeric elements function sortnum (a, B) {return a-B;} Array. prototype. unique1 = function () {this. sort (sortnum); var newnumbers = [this [0]; for (var I = 0; I <this. length; I ++) {if (this [I]! = Newnumbers [newnumbers. length-1]) {newnumbers. push (this [I]) ;}}; return newnumbers ;}; var mynums = [1, 2, 5, 8, 2, 5, 7, 42, 8, 0]; mynums = mynums. unique1 (); console. log (mynums); // The json object can be used to retrieve non-numeric element arrays. prototype. jsonUnique = function () {var json = {}; for (var I = 0; I <this. length; I ++) {if (! Json [this [I]) {json [this [I] = 1 ;}}; return json ;}; var mynumss = [, 54,1, 54, 'haha ', 'haha', 'ours ', 'who', 'who']; mynumss = mynumss. jsonUnique (); for (var key in mynumss) {console. log (key );}

Javascript array deduplication

Arr is an array to be duplicated, and ret is a new array obtained after deduplication. hash is equivalent to a Map to record whether an element already exists in ret.
The program traverses arr and uses the type of each element + this element as the Map key. If the key already exists in the hash, it will not be added to ret, if not, add it to ret and add the new key to hash.

If (hash [key]! = 1) Actually, it is used to determine whether the current element has appeared.

The javascript array should be de-duplicated, and should be effective for no matter how complicated the array is. Write a detailed comment and add 50 points if the answer is satisfactory.

The attributes of the Object in JS are unique. Just make good use of it.
Only one row of country input is valid.

The uniqueness in city is unknown and needs to be treated separately, but it can be processed by name or value,
You must specify one. Is to give your desired processing result as an example for further implementation.