Run results for: substring vs. slice vs. replace to remove string from end of input string

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/139.0.0.0 Safari/537.36 Edg/139.0.0.0

Browser: Chrome 139

Operating system: Windows

Device Platform: Desktop

Date tested: 8 months ago

Test name	Executions per second
Using String.replace()	374.1 Ops/sec
Using String.substring() with a lastIndexOf() search	437.5 Ops/sec
Using String.substring() with a magic number	958.1 Ops/sec
Using String.slice()	965.3 Ops/sec
Using String.slice() without a pre-calculated suffix length	969.5 Ops/sec

Script Preparation code:

var numOfStrings = 100000
var suffix = 'TestStringHere'
var suffixLength = suffix.length
var negSuffixLength = suffixLength * -1
var testStrings = []

// Generate test string as a UUID + the suffix above.
function uuidv4() {
   return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g,
   function(c) {
      var uuid = Math.random() * 16 | 0, v = c == 'x' ? uuid : (uuid & 0x3 | 0x8);
      return uuid.toString(16);
   });
}

for (let i = 0; i < numOfStrings; i++) {
  testStrings.push(uuidv4() + suffix)
}

Tests:

Using String.replace()
testStrings.map(str => { return str.replace(suffix, '') })
Using String.substring() with a lastIndexOf() search
testStrings.map(str => { return str.substring(0, str.lastIndexOf(suffix)) })
Using String.substring() with a magic number
testStrings.map(str => { return str.substring(0, str.length - suffixLength) })
Using String.slice()
testStrings.map(str => { return str.slice(0, negSuffixLength) })
Using String.slice() without a pre-calculated suffix length
testStrings.map(str => { return str.slice(0, suffix.length * -1) })

Run results for: substring vs. slice vs. replace to remove string from end of input string

Determine the fastest way to remove a string from the end of another string.

Using String.replace()

Using String.substring() with a lastIndexOf() search

Using String.substring() with a magic number

Using String.slice()

Using String.slice() without a pre-calculated suffix length