js string interception of Chinese process comprising

First, explain

Chinese string interception is two bytes, a alphanumeric character, Common taken

substr () whether Chinese or letters are taken by one, the processing now taken string containing characters

 

 

Second, examples:

abc def Bi fruit

　　const test = 'ab Bi fruit DEF' ;
    console.log(this.Substr(test, 2, 6));
    console.log(this.Substr(test, 0, 3));

 

 

Third, the code

 // string interception process contains Chinese, str need to intercept the string, start start position of interception, n intercept length 
  Substr (STR, start, n) { // eslint disable-Line- 
    IF (str.replace (/ [\ u4e00 . - \ u9fa5] / G, '**') length <= n-) {
       return STR;
    }
    years as = 0 ;
    tmpStr the let = '' ;
     for (I = Start the let; I <str.length; I ++) { // iterate string 
      IF (/[\u4e00-\u9fa5]/.test(str[i])) { // Chinese two bytes in length 
        len + = 2 ;
      } else {
        only + = 1 ;
      }
      if (len > n) {
        break;
      } else {
        tmpStr += str[i];
      }
    }
    return tmpStr;
  }