How to delete a property of an object in JavaScript

1. delete

delete is the only real way to remove an object's properties without any leftovers, but it works 100 times slower than its "alternative" setting object[key] = undefined

var myObject = {
    "ircEvent": "PRIVMSG",
    "method": "newURI",
    "regex": "^http://.*"
};
delete myObject.regex;

console.log(myObject);

The delete operator removes the specified property from an object. Returns true if the deletion is successful, otherwise returns false. However, the following situations require important consideration:

If the property you are trying to delete does not exist, then delete will have no effect, but will still return true.

If there is a property on the prototype chain of the object with the same name as the property to be deleted, then after deleting the property, the object will use the property on the prototype chain (that is, the delete operation will only work on its own properties)

Any property declared with var cannot be deleted from the global scope or from the scope of a function.

In this case, the delete operation cannot delete any function in the global scope (regardless of whether the function comes from a function declaration or a function expression).

Except for functions in the global scope, which cannot be deleted, functions in objects can be deleted using the delete operation.

Any property declared with let or const cannot be deleted from the scope in which it is declared.

Non-configurable properties cannot be removed. This means that properties of built-in objects like Math, Array, Object and properties set to non-settable using the Object.defineProperty() method cannot be deleted.

2. obj.field = undefined;

This choice is not the correct answer to this question! However, if you use it with care, you can speed up some algorithms significantly. If you use delete in a loop and have problems with performance, read the detailed explanation

 var obj = {
     field: 1     
 };
 obj.field = undefined;

3. Use delete in array

In an array, unlike a plain old object, where using delete leaves garbage in the form, null creates a "hole" in the array and the length remains unchanged.

var array = [1, 2, 3, 4];
delete array[2];
/* Expected result --> [1, 2, 4]
 * Actual result --> [1, 2, null, 4]
 */

4. Using splice in array

arrayObject.splice(index,howmany,item1,.....,itemX)

index: Required. Integer, specifies the position to add/remove items. Use negative numbers to remove items from the array.

The specified position at the end.

howmany: required. The number of items to delete. If set to 0, items will not be deleted.

item1: Optional. The new item added to the array.

var arr = new Array(6)
arr[0] = "George"
arr[1] = "John"
arr[2] = "Thomas"
arr[3] = "James"
arr[4] = "Adrew"
arr[5] = "Martin"

document.write(arr + "<br />")
arr.splice(2,0,"William")
document.write(arr + "<br />")
/*
*George, John, Thomas, James, Andrew, Martin
*George, John, William, Thomas, James, Andrew, Martin
*/

Summarize

This is the end of this article about how to delete a property of an object with JavaScript. For more information about how to delete a property of an object with JavaScript, please search previous articles on 123WORDPRESS.COM or continue to browse the following related articles. I hope you will support 123WORDPRESS.COM in the future!