indexOf()
, that allows us to quickly and easily check for the presence of an element on an array. indexOf()
takes an element as a parameter, and when called, it returns the position, or index, of that element, or -1
if the element does not exist on the array.
For example:
let fruits = ['apples', 'pears', 'oranges', 'peaches', 'pears'];
fruits.indexOf('dates') // returns -1
fruits.indexOf('oranges') // returns 2
fruits.indexOf('pears') // returns 1, the first index at which the element exists
indexOf()
can be incredibly useful for quickly checking for the presence of an element on an array. We have defined a function, quickCheck
, that takes an array and an element as arguments. Modify the function using indexOf()
so that it returns true
if the passed element exists on the array, and false
if it does not.
quickCheck(["squash", "onions", "shallots"], "mushrooms")
should return false
'
testString: 'assert.strictEqual(quickCheck([''squash'', ''onions'', ''shallots''], ''mushrooms''), false, ''quickCheck(["squash", "onions", "shallots"], "mushrooms")
should return false
'');'
- text: 'quickCheck(["squash", "onions", "shallots"], "onions")
should return true
'
testString: 'assert.strictEqual(quickCheck([''squash'', ''onions'', ''shallots''], ''onions''), true, ''quickCheck(["squash", "onions", "shallots"], "onions")
should return true
'');'
- text: 'quickCheck([3, 5, 9, 125, 45, 2], 125)
should return true
'
testString: 'assert.strictEqual(quickCheck([3, 5, 9, 125, 45, 2], 125), true, ''quickCheck([3, 5, 9, 125, 45, 2], 125)
should return true
'');'
- text: 'quickCheck([true, false, false], undefined)
should return false
'
testString: 'assert.strictEqual(quickCheck([true, false, false], undefined), false, ''quickCheck([true, false, false], undefined)
should return false
'');'
- text: The quickCheck
function should utilize the indexOf()
method
testString: 'assert.notStrictEqual(quickCheck.toString().search(/\.indexOf\(/), -1, ''The quickCheck
function should utilize the indexOf()
method'');'
```