The difference between indexof and includes

Array indexof Method

Determine whether a string contains substrings （ If it is included, the position of the string will be returned , Does not include return -1）

grammar ：indexof（searchElement,fromIndex）

fromIndex( Optional . Start at this index to find searchElmentui)

let str = 'orange';
 
str.indexOf('o');  //0
str.indexOf('n');  //3
str.indexOf('c');  //-1

Array includes Method

Determine whether an array contains a specified value （ Include return true, Does not include return false）

grammar ：includes（searchElement,fromIndex）

fromIndex( Optional . Start at this index to find searchElmentui)

var arr = [10,20,30,40,50];

arr.includes(10); //true
arr.includes(10,1); //false

indexof and includes The difference between

Different return values ：

​ includes(): return Boolean type
​ indexof(): Back to a Integers Type value of , Indicates the index of the first occurrence of the current value in the array

NaN and undefined To deal with ：

​ indexoOf() : You can't Match to in array NaN, I can't recognize undefined( Direct to ignore )

​ includes() : can Match to in array NaN, Can also recognize sparse arrays undefined