Script Preparation code:
x
 
var TestString = '+'.repeat(200) + '='.repeat(20000) + '+'.repeat(200);
var regexTrim = function(str, ch) {
    if (ch === ']') ch = '\\]';
    else if (ch === '^') ch = '\\^';
    else if (ch === '\\') ch = '\\\\';
    return str.replace(new RegExp('^[' + ch + ']+|[' + ch + ']+$', 'g'), '');
};
function indexTrim(str, ch) {
    var start = 0, 
        end = str.length;
    while(start < end && str[start] === ch)
        ++start;
    while(end > start && str[end - 1] === ch)
        --end;
    return (start > 0 || end < str.length) ? str.substring(start, end) : str;
}
function booleanTrim(str, ch) {
    return str.split(ch).filter(Boolean).join(ch);
}
function spreadTrim(str, ch) {
    const first = [...str].findIndex(char => char !== ch);
    const last = [...str].reverse().findIndex(char => char !== ch);
    return str.substring(first, str.length - last);
}
function substringTrim(str, ch) {
    while(str.charAt(0)==ch) {
        str = str.substring(1);
    }
    while(str.charAt(str.length-1)==ch) {
        str = str.substring(0,str.length-1);
    }
    return str;
}
function splitTrim(str, ch) {
   let res = str.split(ch);
   return res.length > 1 ? res[1] : res[0];
}
Tests:
  • Index Version (Jason Larke)

     
    indexTrim(TestString, '+');
  • Regex Version (leaf)

     
    regexTrim(TestString, '+')
  • Boolean Filter Version (mbaer3000)

     
    booleanTrim(TestString, '+')
  • Spread Version (Robin F.)

     
    spreadTrim(TestString, '+')
  • Substring Version (Pho3niX83)

     
    substringTrim(TestString, '+')
  • Split Version (CheapSk8)

     
    splitTrim(TestString, '+')
Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Experimental features:

  • Test case name Result
    Index Version (Jason Larke)
    Regex Version (leaf)
    Boolean Filter Version (mbaer3000)
    Spread Version (Robin F.)
    Substring Version (Pho3niX83)
    Split Version (CheapSk8)

    Fastest: N/A

    Slowest: N/A

Latest run results:
Run details: (Test run date: one year ago)
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36 Edg/120.0.0.0
Chrome 120 on Windows
View result in a separate tab
Test name Executions per second
Index Version (Jason Larke) 991832.6 Ops/sec
Regex Version (leaf) 131508.1 Ops/sec
Boolean Filter Version (mbaer3000) 155215.6 Ops/sec
Spread Version (Robin F.) 971.6 Ops/sec
Substring Version (Pho3niX83) 237048.7 Ops/sec
Split Version (CheapSk8) 262914.6 Ops/sec