Stage 3 Draft / March 29, 2016

String.prototype.padStart / padEnd

1String.prototype.padStart( maxLength [ , fillString ] )#

When the padStart method is called, the following steps are taken:

  1. Let O be ? RequireObjectCoercible( this value).
  2. Let S be ? ToString(O).
  3. Let intMaxLength be ? ToLength(maxLength).
  4. Let stringLength be the number of elements in S.
  5. If intMaxLength is not greater than stringLength, return S.
  6. If fillString is undefined, let filler be a string consisting solely of the code unit U+0020 (SPACE).
  7. Else, let filler be ? ToString(fillString).
  8. If filler is the empty String, return S.
  9. Let fillLen be intMaxLength - stringLength.
  10. Let truncatedStringFiller be a new String value consisting of repeated concatenations of filler truncated to length fillLen.
  11. Return a new String value computed by the concatenation of truncatedStringFiller and S.
Note 1The first argument maxLength will be clamped such that it can be no smaller than the length of the this value. Note 2The optional second argument fillString defaults to " " (a string consisting of U+0020 SPACE).

2String.prototype.padEnd( maxLength [ , fillString ] )#

When the padEnd method is called, the following steps are taken:

  1. Let O be ? RequireObjectCoercible( this value).
  2. Let S be ? ToString(O).
  3. Let intMaxLength be ? ToLength(maxLength).
  4. Let stringLength be the number of elements in S.
  5. If intMaxLength is not greater than stringLength, return S.
  6. If fillString is undefined, let filler be a string consisting solely of the code unit U+0020 (SPACE).
  7. Else, let filler be ? ToString(fillString).
  8. If filler is the empty String, return S.
  9. Let fillLen be intMaxLength - stringLength.
  10. Let truncatedStringFiller be a new String value consisting of repeated concatenations of filler truncated to length fillLen.
  11. Return a new String value computed by the concatenation of S and truncatedStringFiller.
Note 1The first argument maxLength will be clamped such that it can be no smaller than the length of the this value. Note 2The optional second argument fillString defaults to " " (a string consisting of U+0020 SPACE).

ACopyright & Software License#

Copyright Notice

© 2016 Jordan Harband

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