String.prototype.trimStart / String.prototype.trimEnd
ECMAScript proposal, specs, tests, and reference implementation for String.prototype.trimStart/trimEnd (plus trimLeft/trimRight).
Stage 4
This proposal is complete and already merged into ECMA262 specification. See the specification text here.
Rationale
ES5 standardized String.prototype.trim. All major engines have also implemented corresponding trimLeft and trimRight functions - without any standard specification.
For consistency with padStart/padEnd we propose trimStart and trimEnd and trimLeft/trimRight as aliases required for web compatibility.
Specification
You can view the spec in ecmarkup or rendered as HTML.
Naming / Aliasing
For consistency with padStart/padEnd the standard functions will be trimStart and trimEnd, however for web compatilibity trimLeft will alias trimStart and trimRight will alias trimEnd. This means String.prototype.trimRight.name will change from "trimRight" to "trimEnd" in most engines. The spec author does not expect this to cause any breakage.
Test262 Coverage
Status of This Proposal
This initial proposal was drafted by @sebmarkbage and the updated spec was drafted by @evilpie with input from @ljharb.
This proposal is currently at stage 4 of the process.
Designated TC39 reviewers: Jordan Harband + Daniel Ehrenberg
Implementations
- V8, in Chrome 66+
- SpiderMonkey, in Firefox 61+
- JSC, in Safari 12+
- ChakraCore