JS judge whether a number is in the set

demand ： Judge IdCar Uniqueness .
describe ： Through investigation API Get all the IdCar, Use HashSet For storage . Return this collection to the front end , Form a double check between the front end and the back end .

There's a problem ： Use... On the front end indexOf() When checking , This value is clearly in the set , But always return to **-1** .
reason ： It's the wrong type . resolvent ： Use the front-end type conversion method Number().

js：
Determine whether a value is in an array ( aggregate ) in .
indexOf()、includes()
https://zhidao.baidu.com/question/425115453.html
Application scenarios ： The front-end check 、 Judgment processing logic .
“ Check one id Whether it has existed , Background check 、 The front end is also verified .
Concrete realization ： Request domain -> Front desk inspection
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