Remove duplicate elements from an array in JavaScript

1<script type= "Text/javascript" >2     vararr = ["B", "A", "a", 2, 3, 3, 2, 1, 4, {}];3Array.prototype.unique =function(){4     varRET = [];5     varo = {};//This object here is actually a temporary container, in the following operation, each time from the array to take an element, and then determine whether the object with this element as the property name exists in the object6     //O, if this element is used for the first time (that is, there is no repetition), it certainly does not exist in the object o, so the next step is to assign a value to this property (the purpose is to make it a7     //a complete object with property name: "Property value", so that the next time a duplicate array element, which is the same property name, will not be added to the object again, and the final guarantee Ret.push (v)8     //The element that this operation puts into the new array is not duplicated)9     varLen = This. Length;Ten      for(vari=0; i<len; i++){ One         varv = This[i]; A         if(!O[v]) { -O[V] = "Hello,world";//assign a value, a placeholder, a number, a string can be - Ret.push (v); the         } -     } -     returnret; - }; + Document.writeln (Arr.unique ()); -</script>

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Remove duplicate elements from an array in JavaScript