.indexOf()
The .indexOf()
method returns the first index at which an element can be found. Returns -1
if the element is not found.
Syntax
array.indexOf(element, startIndex);
The following parameters are used in the .indexOf()
method:
- The
element
to be searched for in thearray
. - The optional
startIndex
position to begin searching from. If one is not given, the search starts from the beginning of the array. Negative indices will offset from the end of thearray
.
Examples
In the example below, the index for the number 12
is logged to the console:
const numbers = [6, 12, 8, 10];const indexOf12 = numbers.indexOf(12);console.log(indexOf12);// Output: 1
If element is not found the result will be -1
:
const pizzaToppings = ['pepperoni', 'olives', 'mushrooms'];const indexOfPineapple = pizzaToppings.indexOf('pineapple');console.log(indexOfPineapple);// Output: -1
Check if color 'blue'
is in the colors
array starting with the second element:
const colors = ['blue', 'orange', 'pink', 'yellow', 'teal'];const checkBlue = colors.indexOf('blue', 1);console.log(checkBlue);// Output: -1
Codebyte Example
Multiple matches will only return the first index where a match occurs: