javascript RegExp_reg_exec_VS_str_match

Posted 2021-05-04

let str = 'PathofExile \nThe world path of Game';

//          match: Reg with/withou `g` flag
let reg = /(path)\s*/ig;
let reg2 = /(path)\s*/i;

let result1 = str.match(reg);

console.log(reg.lastIndex); //  0

//  match with global
console.log(result1);
//  0-x: every matched string

console.log(reg.lastIndex); //  0  Reason: reg is the `Formal Parameter`

//  match without global
let result2 = str.match(reg2);

console.log(result2);
//  0: whole string 1-x: group match

let result3 = reg.exec(str);  

console.log(reg.lastIndex); //  4

let result4 = reg2.exec(str);

console.log(reg.lastIndex); //  0 Explanation: `without` global flag, the lastIndex `always` reset to 0