[Javascript] For in extended Array prototype
Written by Bastien Donjon, Posted in Javascript
If you have extended Array prototype with functions like this :
1 2 3 | Array.prototype.inArray = function(){ console.log('inArray function');} |
The result of your ‘for’ will contain the properties and new functions.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | var values = ['value1', 'value2'];console.log(testArray);// => ["value1", "value2", inArray: function]for(var i in values){ console.log(i + ' : ' + values[i]);}// =>// 0 : value1// 1 : value2// inArray : function (){// console.log('inArray function');// } |
To fix this issue :
Case 1 with hasOwnProperty
1 2 3 4 5 6 7 8 9 | for(var i in values){ if (values.hasOwnProperty(i)) { console.log(i + ' : ' + values[i]); }}// =>// 0 : value1// 1 : value2 |
Case 2 with forEach
1 2 3 4 5 6 7 8 | function logArrayElements(element, index, array) { console.log("a[" + index + "] = " + element);}values.forEach(logArrayElements);// =>// 0 : value1// 1 : value2 |
Run on JsFiddle