Benchmark: temptest - MeasureThat.net

Tests:

array
String.prototype.replaceAt = function(index, char) { var a = this.split(""); a[index] = char; return a.join(""); }; 'abcde'.replaceAt(2,'a')
const array
String.prototype.replaceAt = function(index, char) { const a = this.split(""); a[index] = char; return a.join(""); }; 'abcde'.replaceAt(2,'a')
...array
String.prototype.replaceAt = function(index, char) { var a = [...this]; a[index] = char; return a.join(""); }; 'abcde'.replaceAt(2,'a')
const ...array
String.prototype.replaceAt = function(index, char) { const a = [...this]; a[index] = char; return a.join(""); }; 'abcde'.replaceAt(2,'a')
assign
String.prototype.replaceAt = function(index, char) { return Object.assign([...this], {[index]: char}).join(``); }; 'abcde'.replaceAt(2,'a')

Rendered benchmark preparation results:

Previous results

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Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.138 Safari/537.36

Browser/OS: Chrome 81 on Windows 7

temptest (version: 0)