Method one:

function byteLength(str) {
 var byteLen = 0, len = str.length;
 if( !str ) return 0;
 for( var i=0; i<len; i++ )
  byteLen += str.charCodeAt(i) > 255 ? 2 : 1;
 return byteLen;
}

Description: byteLength (STR) Parameters: String STR: a string to calculate the length of bytes (non-ascii characters count 2 bytes)

Method 2:

JS gets the actual length of the string!

Add a little thing today! A programmer often needs to use the string length detection method, because the original length of JS Chinese and English as a character for a length. So it’s up to you to figure out what the actual length of the string is.

function GetLength(str) {
    /// <Summary> Get the actual length of the string, Chinese 2, English 1</ summary>
    /// <Param name = "STR"> To get a string of length </ param>
    var realLength = 0, len = str.length, charCode = -1;
    for (var i = 0; i < len; i++) {
        charCode = str.charCodeAt(i);
        if (charCode >= 0 && charCode <= 128) realLength += 1;
        else realLength += 2;
    }
    return realLength;
};  

Execution code:

Alert (GetLength(’ test tests ceshiceshi));      

Method 3: temporarily failed the test

function getByteLen(val) {
var len = 0;
for (var i = 0; i < val.length; i++) {
if (val[i].match(/[u4e00-u9fa5 ]/ig) != null)
len += 2;
else
len += 1;
}
return len;
}

Method 4:

GBK length calculation function:

//GBK character set actual length calculation
function getStrLeng(str){
    var realLength = 0;
    var len = str.length;
    var charCode = -1;
    for(var i = 0; i < len; i++){
        charCode = str.charCodeAt(i);
        if (charCode >= 0 && charCode <= 128) { 
            realLength += 1;
        }else{ 
            //If it's Chinese, the length is plus 2
            realLength += 2;
        }
    } 
    return realLength;
}

UTF8 length calculation function:

//UTF8 character set actual length calculation
function getStrLeng(str){
    var realLength = 0;
    var len = str.length;
    var charCode = -1;
    for(var i = 0; i < len; i++){
        charCode = str.charCodeAt(i);
        if (charCode >= 0 && charCode <= 128) { 
            realLength += 1;
        }else{ 
            //If it's Chinese, the length is plus 3
            realLength += 3;
        }
    } 
    return realLength;
}