JavaScript数组解构分配和空值

Question

I'm using an external service getListOfItemsFromServiceA which accepts an id (of user) and returns a list of 5 items (exactly 5) associated to this user.

I used Array destructuring assignment to set the value of those items which is working fine like this (just an example):

 var item1, item2, item3, item4, item5; //var result = getListOfItemsFromServiceA(1622); var exampleResult = ['item1', 'item2', 'item3', 'item4', 'item5']; [item1, item2, item3, item4, item5] = exampleResult; console.log(item1, item2, item3, item4, item5); 

The problem I have is that in some cases getListOfItemsFromServiceA(id) returns null for example when the id is not found in the database. So my code is not working:

 var item1, item2, item3, item4, item5; //var result = getListOfItemsFromServiceA(1622); var exampleResult = null; [item1, item2, item3, item4, item5] = exampleResult; console.log(item1, item2, item3, item4, item5); 

Is there a way to solve this using Array destructing syntax instead of adding an if condition like if(getListOfItemsFromServiceA(1622) !== null) ?

Note

• I can't change the code of getListOfItemsFromServiceA .

Answer 1

做这个：

[item1, item2, item3, item4, item5] = exampleResult || [];

Answer 2

You can add a fallback if exampleResult is null :

 var item1, item2, item3, item4, item5; var exampleResult = null; [item1, item2, item3, item4, item5] = exampleResult || []; console.log(item1, item2, item3, item4, item5); 

This produces undefined, undefined, undefined, undefined, undefined .

You can also set default values to the destructured variables :

 var item1, item2, item3, item4, item5; var exampleResult = null; [item1="", item2="", item3="", item4="", item5=""] = exampleResult || []; console.log(item1, item2, item3, item4, item5);