I would like to know whats wrong with my code. As in the title descripted I would like to turn around the content of an array with a for loop to another array. I would like to use ES5 for this since I am not used to ES6+ yet.
Here is my code:
var arrayA = ["h","e","l","l","o"]; var arrayB = []; function copyArray(oldArray, newArray) { oldArray.forEach(function() { var storeElement = oldArray.pop(); newArray.push(storeElement); }); console.log(oldArray + " old array"); console.log(newArray + " new array"); } copyArray(arrayA, arrayB);
The result is:
"h,e,l,l old array" "o new array" "h,e,l old array" "o,l new array" "h,e old array" "o,l,l new array" "h,e FINAL old array" "o,l,l FINAL new array"
But it should be:
"" FINAL old array "o, l, l, e, h" FINAL new array.
What is going wrong?
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Answer
Ok so Issue is your forEach
which not running with oldArray
length
mean 5 times
Why this is happening? It is because you are poping out value withing forEach
which change the length and data of forEach
.
You can check by putting console.log(oldArray);
in forEach
.
var arrayA = ["h", "e", "l", "l", "o"]; var arrayB = []; function copyArray(oldArray, newArray) { var length = oldArray.length; for (var i = 0; i < length; i++) { var storeElement = oldArray.pop(); newArray.push(storeElement); }; console.log(oldArray + " old array"); console.log(newArray + " new array"); } copyArray(arrayA, arrayB); var reverseArray = ["h", "e", "l", "l", "o"].reverse(); console.log("reverse array"); console.log(reverseArray);