ES2017 [1]. The MDN docs always link the latest version of the spec; the year in the link doesn't correspond to the version where it was added. The proposal was already mostly done at the time of the incident [2]
[1] https://tc39.es/ecma262/2017/#sec-string.prototype.padstart [2] https://github.com/tc39/proposal-string-pad-start-end
ES2017 [1]. The MDN docs always link the latest version of the spec; the year in the link doesn't correspond to the version where it was added. The proposal was already mostly done at the time of the incident [2]
[1] https://tc39.es/ecma262/2017/#sec-string.prototype.padstart [2] https://github.com/tc39/proposal-string-pad-start-end