$ Set and array update Methods in vue. js, and vue. jsset array update

$ Set and array update Methods in vue. js, and vue. jsset array update

Due to JavaScript restrictions, Vue cannot detect the following changed Arrays:

When an array item is directly set using indexes, such as vm. items [indexOfItem] = newValue

When you modify the length of an array, such as vm. items. length = newLength, the array is not updated.

Of course, the solution provided in vue is to use Vue. set, vm. $ set (Vue. modify the array, such as splice and caoncat, and trigger status update:

Ex:

Therefore, if you add a new property to the instance after the instance is created, the update is not triggered.

Ps:Now there are two Arrays: arr1 and arr2. If the values below arr1 change the array, what is the result of changing the array with $ set?

Data: {arr1 = ['A', 'B', 'C']; arr2 = ['foo', 'bar', 'baz'];} vm. arr1 [1] = 'alpha'; vm. $ set (vm. arr2, 1, 'alpha ');

Changing the array according to the subscript index at the beginning cannot trigger status update. We will know that the second change of the first array will not be updated on the page, only changes to the second array will be updated on the page. However, the result is:

Arr1 = ['A', 'alpha', 'B', 'C']; arr2 = ['foo', 'alpha', 'bar', 'baz'];

The values of the two arrays are updated. That is to say, when arr2 is updated using the $ set () method, the page is updated again.

In the above vue. js, $ set and array update methods are all the content shared by xiaobian. I hope to give you a reference, and I hope you can provide more support for the customer's house.