STR = the let ' abcdef ' ; // 0 STR = str.slice ( 0 ); // return the whole string abcdef STR = str.substring ( 0 ); // return the whole string abcdef STR = str.substr ( 0 ) ; // return the entire string abcdef // use a parameter STR = str.slice ( 2 ); // taken after all of the characters in the second CDEF STR = str.substring ( 2 ;) // all taken after the second character CDEF STR = str.substr ( 2 ); // taken after all of the characters in the second CDEF // use two parameters STR = str.slice ( 2, 4 ); // taken cd characters between the second through fourth STR = str.substring ( 2 , 4 ); // taken cd characters between the second through fourth str = str.substr ( 2 , 4 ); // taken from the 3rd onward cdef characters between the number 4 // use two negative STR str.slice = ( . 1 , - . 3 ); // taken first to the second bc between four characters STR str.substring = ( . 1 , - . 3 ); // taken characters between the second to fourth converted to negative a # 0 STR str.substr = ( . 1 , - . 3 ) ; // can not be negative, if negative force transmission, will be processed as 0 '' is converted to a negative number # 0 the console.log (STR) 0 ----------------