How does vue empty an array

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1. Preface

Two days ago, I encountered a problem at work: how to empty the responsive array generated by reactive in vue3. Of course, this is what I usually write:

Let array = [1, 2, 3]; array = []

However, there is still a problem with the way it is used in the reactive proxy, such as this:

Let array = reactive ([1 array 2)]); watch () = > [... array], () = > {console.log (array);},) array = reactive ([])

Obviously, because the reference to the original responsive object is lost, the monitoring is lost directly.

two。 Several ways of emptying data

Of course, as a decade code experience, I immediately came up with several solutions.

2.1 use ref ()

With ref, this is the easiest way to:

Const array = ref ([1Jing 2jue 3]); watch (array, () = > {console.log (array.value);},) array.value = []

2.2 using slice

Slice, as its name implies, is to slice an array and return a new array, which feels a bit like slicing in go. Of course, friends who have used react should often use slice. To empty an array, you only need to write:

Const array = ref; watch (array, () = > {console.log (array.value);},) array.value = array.value.slice (0mem0)

However, you need to be careful to use ref.

2.3 length assigned to 0

Personally, I prefer this, and directly assign length to 0:

Const array = ref ([1Jing 2jue 3]); watch (array, () = > {console.log (array.value);}, {deep:true}) array.value.length = 0

Also, this will only trigger once, but you need to note that watch needs to turn on deep:

However, in this way, it is more convenient to use reactive without having to open deep:

Const array = reactive ([1 array 2]); watch (() = > [... array], () = > {console.log (array);}) array.length = 0

2.4 using splice

The side effect function splice is also a solution, in which case you can also use reactive:

Const array = reactive ([1J2 array 3]); watch (() = > [... array], () = > {console.log (array);},) array.splice (0journal array.length)

Note, however, that watch triggers multiple times:

Of course, you can also use ref, but note that in this case, you need to turn on deep:

Const array = ref, watch (array, () = > {console.log (array.value);}, {deep:true}) array.value.splice (0meme array.value.length)

But you can see that ref, like reactive, triggers multiple times.

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