The forEach
method in Javascript iterates over the elements of an array and calls the provided function for each element in order.
Note:
forEach
only works on arrays. It does not execute a function for an array without any elements.
It is written in the following form:
array: the array on which the specified function is called.
forEach: the method called for the array with the required parameters.
function(currentValue, index, arr): the function with its parameters which is required to run for each element of the array.
currentValue: the value of the current element.
index: the index of the current element being processed.
arr: the array object on which function was called.
thisValue: value to be used as the function’s this
value when executing it. “undefined” is passed if this value is not provided.
Note: index, arr and thisValue are all optional parameters.
Here’s an example implementing forEach
in Javascript:
var arr = ['Wall-E', 'Up', 'Coco'];arr.forEach(function(item) {console.log(item);})
In the code above, the forEach()
method calls the provided function for each element of arr
in order. item
is used to store the current value and as a result, all the elements of the array are displayed on to the console one by one.
No optional parameters have been passed in this case. The code below uses optional parameters.
var arr = [5,4,8,7];arr.forEach(function(item,index,arr) {console.log("item: " + item + " at index: " + index + " in the array: " + arr);})