Basic Arrays Labs
Resources for this lab: resources/labs/basicArrays
1 : Create an array literal in a variable named testArray¶
The array should contain the values :
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0-10
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'apple','banana'and'coconut' -
undefined -
NaN
2 : Write a function expression named countElements ...¶
The function will take a single argument (an array), and should return the length of the array
3 : Write a function expression named countType ...¶
The function will take two arguments:
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the first argument is an array
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the second argument is the string representation of a type (e.g. 'number')
The function should return the number of that type of value contained within the array
4 : Write a function expression named countTypeWithFunction ...¶
The previous function was useful, but obviously flawed. We are simply testing for
type, but it is unlikely that we would want to include NaN in that count.
Unfortunately for us, NaN's type is 'number'. To circumvent this, we will pass
a new function (countTypeWithFunction) which uses some specific logic to determine if a number should be counted.
countTypeWithFunction will accept two arguments:
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the first argument should be an array
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the second argument is a function
The function will evaluate a single element of the array and determine if it should be included (return true), or not (return false).
Write three function expressions to pass to your countTypeWithFunction function :
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isRealNumber
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isString
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isUndefined
Each takes one argument (the current value), and returns true or false depending on if the value is of the desired type.
5 : Create a function expression named concurrentModification ...¶
concurrentModification takes two arguments:
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the first argument is an array
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the second argument is a function
Your objective is to remove all of the real numbers from the array. There is a
function (splice) which will help you remove items from a JavaScript array. splice
does many things, but you can remove a single value by passing the index
of that value and the number 1 to splice as arguments (array.splice(i,1);).
Unlike Java, JavaScript will not throw any sort of 'ConcurrentModificationException', if you modify an array as you iterate over it... but there are other consequences... this exercise should familiarize you with those.
Once you have removed all of the numbers from the array, return the resulting array.