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      • String.prototype.{trimStart,trimEnd} S4

      Proposal details
      Proposal overview

      This proposal aims to standardize String.prototype.trimStart and trimEnd methods, which trim whitespace from the beginning or end of a string, respectively. It also introduces trimLeft and trimRight as aliases to ensure web compatibility, matching the naming pattern of padStart/padEnd.

      Note

      The README below comes from the upstream repository and may contain outdated stage or status metadata. Use the proposal details above as the current source of truth.

      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

      PR open

      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