Can use splice but cannot use substring

Question

Why do I get an error when using substring for the same array?

Answer 1

The

substring() method is used to extract characters between two specified subscripts in a string.

Syntax: stringObject.substring(start,stop)

Cannot be used directly on arrays. Please refer to JavaScript substring() method

Answer 2

substring, as the name suggests, is a function of string.

Answer 3

substring is used to operate strings. It is recommended to use slice instead.

Answer 4

splice is the value returned by deletion, oppArr has been changed and becomes empty;
splice(0) is to clear the array; slice(start, end) is to intercept the array and will not change the original array;
substring is to intercept the string Method