javascript tutorial - [Solved-5 Solutions] Array elements at beginning - javascript - java script - javascript array
Problem:
How to add new array elements at the beginning of an array in JavaScript?
Solution 1:
[23, 45, 12, 67]
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And the response from our AJAX call is 34,
[34, 23, 45, 12, 67]
var newArray = [];
newArray.push(response);
for (int i = 0; i < theArray.length; i++) {
newArray.push(theArray[i]);
}
theArray = newArray;
delete newArray;
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Solution 2:
Use unshift . It's like push , except it adds elements to the beginning of the array instead of the end.
unshift/push- add an element to the beginning/end of an arrayshift/pop- remove and return the first/last element of and array
A simple diagram...
unshift -> array <- push
shift <- array -> pop
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and chart:
add remove start end
push X X
pop X X
unshift X X
shift X X
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Solution 3:
var a = [23, 45, 12, 67];
a.unshift(34);
console.log(a); // [34, 23, 45, 12, 67]
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Solution 4:
* array_unshift() - (aka Prepend ;; InsertBefore ;; InsertAtBegin )
* array_shift() - (aka UnPrepend ;; RemoveBefore ;; RemoveFromBegin )
* array_push() - (aka Append ;; InsertAfter ;; InsertAtEnd )
* array_pop() - (aka UnAppend ;; RemoveAfter ;; RemoveFromEnd )
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Solution 5:
function fn_unshift() {
arr.unshift(0);
return arr;
}
function fn_concat_init() {
return [0].concat(arr)
}