10.Array Methods in Javascript push() pop() shift() unshift() slice() - add/remove Operations
Welcome to the series of javascript 2019 part 10
By the end of this video you will be able to
1.Add elements to the array from the end
2. Add elements to the array from the beginning
3.Remove from both the sides
4.Take a sub part of the arrays
The push method appends values to an array.
push is intentionally generic. This method can be used with call() or apply() on objects resembling arrays. The push method relies on a length property to determine where to start inserting the given values. If the length property cannot be converted into a number, the index used is 0. This includes the possibility of length being nonexistent, in which case length will also be created.
Although strings are native, Array-like objects, they are not suitable in applications of this method, as strings are immutable. Similarly for the native, Array-like object arguments.
The pop method removes the last element from an array and returns that value to the caller.
pop is intentionally generic; this method can be called or applied to objects resembling arrays. Objects which do not contain a length property reflecting the last in a series of consecutive, zero-based numerical properties may not behave in any meaningful manner.
If you call pop() on an empty array, it returns undefined.
The shift method removes the element at the zeroeth index and shifts the values at consecutive indexes down, then returns the removed value. If the length property is 0, undefined is returned.
shift is intentionally generic; this method can be called or applied to objects resembling arrays. Objects which do not contain a length property reflecting the last in a series of consecutive, zero-based numerical properties may not behave in any meaningful manner.
Array.prototype.pop() has similar behavior to shift, but applied to the last element in an array.
The unshift method inserts the given values to the beginning of an array-like object.
unshift is intentionally generic; this method can be called or applied to objects resembling arrays. Objects which do not contain a length property reflecting the last in a series of consecutive, zero-based numerical properties may not behave in any meaningful manner.
Please note that, if multiple elements are passed as parameters, they're inserted in chunk at the beginning of the object, in the exact same order they were passed as parameters. Hence, calling unshift with n arguments once, or calling it n times with 1 argument (with a loop, for example),
slice does not alter the original array. It returns a shallow copy of elements from the original array. Elements of the original array are copied into the returned array as follows:
For object references (and not the actual object), slice copies object references into the new array. Both the original and new array refer to the same object. If a referenced object changes, the changes are visible to both the new and original arrays.
For strings, numbers and booleans (not String, Number and Boolean objects), slice copies the values into the new array. Changes to the string, number or boolean in one array do not affect the other array.
If a new element is added to either array, the other array is not affected.
Following methods are discussed
1.Push()
2.Pop();
3.Shift();
4.unshift();
5.slice();
#ArrayMethods #Adding #Slice #shift
10 Array Methods in Javascript push() pop() shift() unshift() slice() - add/remove Operations