譛ャ鬆√�逶ョ谺。 逶ョ谺。

15.7 Number 繧ェ繝悶ず繧ァ繧ッ繝� (Number Objects)

15.7.1 髢「謨ー縺ィ縺励※蜻シ縺ー繧後k Number 繧ウ繝ウ繧ケ繝医Λ繧ッ繧ソ (The Number Constructor Called as a Function)

繧ウ繝ウ繧ケ繝医Λ繧ッ繧ソ縺ァ縺ッ縺ェ縺城未謨ー縺ィ縺励※蜻シ蜃コ縺輔l繧� Number 縺ッ縲∝梛螟画鋤繧定。後≧縲�

15.7.1.1 Number ( [ value ] )

value 縺御セ帷オヲ縺輔l繧後� ToNumber(value) 縺ォ繧医j邂怜�縺励◆ (Number 繧ェ繝悶ず繧ァ繧ッ繝医〒縺ッ縺ェ縺�) 謨ー蛟、繧定ソ斐@縲∽セ帷オヲ縺輔l縺ェ縺代l縺ー +0 繧定ソ斐☆縲�

15.7.2 Number 繧ウ繝ウ繧ケ繝医Λ繧ッ繧ソ (The Number Constructor)

new 蠑上�荳€驛ィ縺ィ縺励※蜻シ蜃コ縺輔l繧� Number 縺ッ繧ウ繝ウ繧ケ繝医Λ繧ッ繧ソ縺ァ縺ゅk: 譁ー隕上↓逕滓�縺励◆繧ェ繝悶ず繧ァ繧ッ繝医r蛻晄悄蛹悶☆繧九€�

15.7.2.1 new Number ( [ value ] )

譁ー隕上↓讒狗ッ峨&繧後◆繧ェ繝悶ず繧ァ繧ッ繝医� [[Prototype]] 繝励Ο繝代ユ繧」縺ッ縲� Number.prototype (繧サ繧ッ繧キ繝ァ繝ウ 15.7.3.1) 縺ョ蛻晄悄蛟、縺ァ縺ゅk縲√が繝ェ繧ク繝翫Ν縺ョ Number 繝励Ο繝医ち繧、繝励が繝悶ず繧ァ繧ッ繝医↓險ュ螳壹&繧後k縲�

譁ー隕上↓讒狗ッ峨&繧後◆繧ェ繝悶ず繧ァ繧ッ繝医� [[Class]] 繝励Ο繝代ユ繧」縺ッ縲� "Number" 縺ォ險ュ螳壹&繧後k縲�

譁ー隕上↓讒狗ッ峨&繧後◆繧ェ繝悶ず繧ァ繧ッ繝医� [[Value]] 繝励Ο繝代ユ繧」縺ッ縲� value 縺御セ帷オヲ縺輔l繧九↑繧峨� ToNumber(value) 縺ォ縲√◎縺�〒縺ェ縺代l縺ー +0 縺ォ險ュ螳壹&繧後k縲�

15.7.3 Number 繧ウ繝ウ繧ケ繝医Λ繧ッ繧ソ縺ョ繝励Ο繝代ユ繧」 (Properties of the Number Constructor)

Number 繧ウ繝ウ繧ケ繝医Λ繧ッ繧ソ縺ョ蜀�Κ [[Prototype]] 繝励Ο繝代ユ繧」縺ョ蛟、縺ッ縲� Function 繝励Ο繝医ち繧、繝励が繝悶ず繧ァ繧ッ繝� (繧サ繧ッ繧キ繝ァ繝ウ 15.3.4) 縺ァ縺ゅk縲�

蜀�Κ繝励Ο繝代ユ繧」縺ィ length 繝励Ο繝代ユ繧」 (蛟、縺ッ 1) 縺ョ莉悶↓縲� Number 繧ウ繝ウ繧ケ繝医Λ繧ッ繧ソ縺ッ谺。縺ョ繝励Ο繝代ユ繧」繧呈戟縺、:

15.7.3.1 Number.prototype

Number.prototype 縺ョ蛻晄悄蛟、縺ッ Number 繝励Ο繝医ち繧、繝励が繝悶ず繧ァ繧ッ繝� (繧サ繧ッ繧キ繝ァ繝ウ 15.7.4) 縺ァ縺ゅk縲�

縺薙�繝励Ο繝代ユ繧」縺ッ縲∝ア樊€ァ { DontEnum, DontDelete, ReadOnly } 縺ァ縺ゅk縲�

15.7.3.2 Number.MAX_VALUE

Number.MAX_VALUE 縺ョ蛟、縺ッ縲¨umber 蝙九�豁」縺ョ譛蛾剞謨ー縺ョ譛€螟ァ蛟、縺ァ縺ゅj縲√♀縺翫h縺� 1.7976931348623157 テ� 10308 縺ァ縺ゅk縲�

縺薙�繝励Ο繝代ユ繧」縺ッ縲∝ア樊€ァ{ DontEnum, DontDelete, ReadOnly } 繧呈戟縺、縲�

15.7.3.3 Number.MIN_VALUE

Number.MIN_VALUE 縺ョ蛟、縺ッ Number 蝙九�豁」縺ョ譛€蟆丞€、縺ァ縺ゅj縲√♀縺翫h縺� 5 テ� 10-324.

縺薙�繝励Ο繝代ユ繧」縺ッ縲∝ア樊€ァ { DontEnum, DontDelete, ReadOnly } 縺ァ縺ゅk縲�

15.7.3.4 Number.NaN

Number.NaN 縺ョ蛟、縺ッ NaN 縺ァ縺ゅk縲�

縺薙�繝励Ο繝代ユ繧」縺ッ縲∝ア樊€ァ { DontEnum, DontDelete, ReadOnly } 縺ァ縺ゅk縲�

15.7.3.5 Number.NEGATIVE_INFINITY

Number.NEGATIVE_INFINITY 縺ョ蛟、縺ッ縲� -竏� 縺ァ縺ゅk縲�

縺薙�繝励Ο繝代ユ繧」縺ッ縲∝ア樊€ァ { DontEnum, DontDelete, ReadOnly } 縺ァ縺ゅk縲�

15.7.3.6 Number.POSITIVE_INFINITY

Number.POSITIVE_INFINITY 縺ョ蛟、縺ッ縲� +竏� 縺ァ縺ゅk縲�

縺薙�繝励Ο繝代ユ繧」縺ッ縲∝ア樊€ァ { DontEnum, DontDelete, ReadOnly } 縺ァ縺ゅk縲�

15.7.4 Number 繝励Ο繝医ち繧、繝励が繝悶ず繧ァ繧ッ繝医�繝励Ο繝代ユ繧」 (Properties of the Number Prototype Object)

Number 繝励Ο繝医ち繧、繝励が繝悶ず繧ァ繧ッ繝� 縺ッ縲√◎繧瑚�霄ォ 蛟、縺� +0 縺ョ Number 繧ェ繝悶ず繧ァ繧ッ繝� ([[Class]] 縺� "Number") 縺ァ縺ゅk縲�

Number 繝励Ο繝医ち繧、繝励が繝悶ず繧ァ繧ッ繝医�蜀�Κ [[Prototype]] 繝励Ο繝代ユ繧」縺ョ蛟、縺ッ縲� Object 繝励Ο繝医ち繧、繝励が繝悶ず繧ァ繧ッ繝� (繧サ繧ッ繧キ繝ァ繝ウ 15.2.3.1) 縺ァ縺ゅk縲�

莉・髯阪€� Number 繝励Ο繝医ち繧、繝励が繝悶ず繧ァ繧ッ繝医�繝励Ο繝代ユ繧」縺ァ縺ゅk髢「謨ー縺ョ隱ャ譏弱↓縺翫>縺ヲ縲√ヵ繝ャ繝シ繧コ "縺薙� Number 繧ェ繝悶ず繧ァ繧ッ繝�" 縺ッ縲�未謨ー縺ョ蜻シ蜃コ縺励↓縺ィ縺」縺ヲ縺ョ this 蛟、縺ァ縺ゅk繧ェ繝悶ず繧ァ繧ッ繝医r蜿ら�縺吶k; this 蛟、縺後が繝悶ず繧ァ繧ッ繝医〒縺ッ縺ェ縺上€∝�驛ィ [[Class]] 繝励Ο繝代ユ繧」縺ョ蛟、縺� "Number" 縺ェ繧峨�縲∽セ句、� TypeError 縺梧兜縺偵i繧後k縲� 縺セ縺溘€√ヵ繝ャ繝シ繧コ "縺薙�謨ー蛟、" 縺ッ縲√%縺ョ Number 繧ェ繝悶ず繧ァ繧ッ繝医〒縺ゅi繧上&繧後k謨ー蛟、縲√▽縺セ繧翫€√%縺ョ Number object 縺ョ蜀�Κ [[Value]] 繝励Ο繝代ユ繧」縺ョ蛟、繧貞盾辣ァ縺吶k縲�

15.7.4.1 Number.prototype.constructor

Number.prototype.constructor 縺ョ蛻晄悄蛟、縺ッ縲∫オ�セシ縺ソ Number 繧ウ繝ウ繧ケ繝医Λ繧ッ繧ソ縺ァ縺ゅk縲�

15.7.4.2 Number.prototype.toString (radix)

radix 縺梧焚 10 縺セ縺溘� undefined 縺ェ繧峨�縲√%縺ョ謨ー蛟、縺ッ蠑墓焚縺ィ縺励※ ToString 貍皮ョ怜ュ舌↓荳弱∴繧峨l繧�; 邨先棡縺ョ譁�ュ怜�蛟、縺瑚ソ斐&繧後k縲�

radix 縺� 2 縺九i 36 縺ョ謨エ謨ー縺ァ縲� 10 縺ァ縺ェ縺�↑繧峨�縲∫オ先棡縺ッ譁�ュ怜�縺ァ縲∝ョ溯」�セ晏ュ倥�驕ク謚槭→縺ェ繧九€�

toString 髢「謨ー縺ッ豎守畑逧�〒縺ッ縺ェ縺�; this 蛟、縺� Number 繧ェ繝悶ず繧ァ繧ッ繝医〒縺ェ縺代l縺ー縲∽セ句、� TypeError 繧呈兜縺偵k縲ゅ◎繧後f縺医€∽サ悶�遞ョ鬘槭�繧ェ繝悶ず繧ァ繧ッ繝医↓繝。繧ス繝�ラ縺ィ縺励※霆「逕ィ縺ァ縺阪↑縺�€�

15.7.4.3 Number.prototype.toLocaleString()

繝帙せ繝育腸蠅��迴セ蝨ィ縺ョ繝ュ繧ア繝シ繝ォ縺ョ諷」鄙偵↓豐ソ縺」縺ヲ謨エ蠖「縺輔l繧� Number 縺ョ蛟、繧定。ィ縺呎枚蟄怜�蛟、繧堤函謌舌☆繧九€ゅ%縺ョ髢「謨ー縺ッ螳溯」�セ晏ュ倥〒縲� toString 縺ィ蜷後§繧ゅ�繧定ソ斐☆縺薙→繧定ィア蜿ッ縺輔l縺ヲ縺�k縺梧耳螂ィ繧ゅ&繧後↑縺�€�

NOTE 縺薙�髢「謨ー縺ョ隨ャ荳€繝代Λ繝。繝シ繧ソ縺ッ縲√%縺ョ讓呎コ悶�蟆�擂縺ョ繝舌�繧ク繝ァ繝ウ縺ァ菴ソ逕ィ縺輔l繧句庄閭ス諤ァ縺後≠繧�; 螳溯」��縺薙�繝代Λ繝。繝シ繧ソ繧剃サ悶�逕ィ騾斐↓菴ソ逕ィ縺励↑縺�%縺ィ繧呈耳螂ィ縺吶k縲�

15.7.4.4 Number.prototype.valueOf ( )

縺薙�謨ー蛟、繧定ソ斐☆縲�

valueOf 髢「謨ー縺ッ豎守畑逧�〒縺ッ縺ェ縺�; this 蛟、縺� Number 繧ェ繝悶ず繧ァ繧ッ繝医〒縺ェ縺代l縺ー縲∽セ句、� TypeError 繧呈兜縺偵k縲ゅ◎繧後f縺医€∽サ悶�遞ョ鬘槭�繧ェ繝悶ず繧ァ繧ッ繝医↓繝。繧ス繝�ラ縺ィ縺励※霆「逕ィ縺ァ縺阪↑縺�€�

15.7.4.5 Number.prototype.toFixed (fractionDigits)

蟆乗焚轤ケ縺ョ蠕後� fractionDigits 蛟九�謨ー蟄励↓縺」縺ヲ謨ー繧貞崋螳夂せ陦ィ險� (fixed-point notation) 縺吶k譁�ュ怜�繧定ソ斐☆縲� fractionDigits 縺� undefined 縺ェ繧峨�縲� 0 縺御サョ螳壹&繧後k縲� 蜈キ菴鍋噪縺ォ縺ッ縲∵ャ。縺ョ繧ケ繝�ャ繝励r螳溯。後☆繧�:

  1. f 繧� ToInteger(fractionDigits) 縺ィ縺吶k縲� (fractionDigits 縺� undefined 縺ェ繧峨�縲� 縺薙�繧ケ繝�ャ繝励�蛟、 0 繧堤函謌舌☆繧�)
  2. f < 0 縺セ縺溘� f > 20 縺ェ繧峨�縲� 萓句、� RangeError 繧呈兜縺偵k縲�
  3. x 繧� 縺薙�謨ー蛟、 縺ィ縺吶k縲�
  4. x 縺� NaN 縺ェ繧峨�縲∵枚蟄怜� "NaN" 繧定ソ斐☆縲�
  5. s 繧堤ゥコ譁�ュ怜�縺ィ縺吶k縲�
  6. x ≥ 0 縺ェ繧峨�縲� 繧ケ繝�ャ繝� 9 縺ク縲�
  7. s 繧� "-" 縺ィ縺吶k縲�
  8. x = - x 縺ィ縺吶k縲�
  9. x ≥ 1021 縺ェ繧峨�縲� m = ToString(x) 縺ィ縺励€� 繧ケ繝�ャ繝� 20 縺ク縲�
  10. n 繧偵€� n ÷ 10f - x 縺ョ 蜴ウ蟇�↑謨ー蟄ヲ蛟、縺悟庄閭ス縺ェ髯舌j 0 縺ォ霑代>繧医≧縺ェ謨エ謨ー縺ィ縺吶k縲ゅ◎縺ョ繧医≧縺ェ n 縺� 2 蛟九≠繧後�縲∝、ァ縺阪>譁ケ繧� n 縺ィ縺吶k縲�
  11. n = 0 縺ェ繧峨�縲� m 繧呈枚蟄怜� "0" 縺ィ縺吶k縲� 縺昴≧縺ァ縺ェ縺代l縺ー縲� m 繧偵€� n 繧� 10 騾イ謨ー縺ァ縺ゅi繧上☆謨ー蟄励〒讒区�縺輔l繧区枚蟄怜�縺ィ縺吶k (鬆�コ上〒 0 縺ッ蜈郁。後@縺ェ縺�)縲�
  12. f = 0 縺ェ繧峨�縲� 繧ケ繝�ャ繝� 20 縺ク縲�
  13. k 繧� m 縺ョ譁�ュ玲焚縺ィ縺吶k縲�
  14. k > f 縺ェ繧峨�縲� 繧ケ繝�ャ繝� 18 縺ク縲�
  15. z 繧偵€� f + 1 - k 蛟九�譁�ュ� '0' 縺ァ讒区�縺輔l繧区枚蟄怜�縺ィ縺吶k縲�
  16. m 繧呈枚蟄怜� z 縺ィ m 縺ョ騾」邨舌→縺吶k縲�
  17. k = f + 1 縺ィ縺吶k縲�
  18. a 繧� m 縺ョ蜈磯�ュ縺ョ k - f 蛟九�譁�ュ励→縺励€� b 繧� m 縺ョ谿九j縺ョ f 蛟九�譁�ュ励→縺吶k縲�
  19. m 繧� 3 蛟九�譁�ュ怜� a, ".", b 縺ョ騾」邨舌→縺吶k縲�
  20. 譁�ュ怜� s 縺ィ m 縺ョ騾」邨舌r霑斐☆縲�

toFixed 繝。繧ス繝�ラ縺ョ length 繝励Ο繝代ユ繧」縺ッ 1 縺ァ縺ゅk縲�

toFixed 繝。繧ス繝�ラ縺後€� 2 蛟倶サ・荳翫�蠑墓焚縺ァ蜻シ蜃コ縺輔l繧九↑繧峨�縲∵険繧玖�縺��譛ェ螳夂セゥ縺ァ縺ゅk (繧サ繧ッ繧キ繝ァ繝ウ 15 蜿ら�)縲�

螳溯」��縲� 0 譛ェ貅€繧� 20 繧医j螟ァ縺阪> fractionDigits 縺ョ蛟、縺ォ蟇セ縺吶k toFixed 縺ョ謖ッ繧玖�縺��諡。蠑オ繧定ィア蜿ッ縺輔l繧九€ゅ%縺ョ蝣エ蜷医€� toFixed 縺ッ縺昴�繧医≧縺ェ蛟、縺ォ蟇セ縺� RangeError 繧呈兜縺偵k蠢�ヲ√�縺ェ縺�€�

NOTE toFixed 縺ョ蜃コ蜉帙�縲∝€、縺ォ繧医▲縺ヲ縺ッ toString 繧医j豁」遒コ縺ァ繧医¥縲√◎繧後� toString 縺碁團謗・縺励◆謨ー蛟、縺九i謨ー繧貞玄蛻・縺吶k縺ョ縺ォ蜊∝�縺ェ譯∵焚繧貞�蜉帙☆繧九□縺代□縺九i縺ァ縺ゅk縲ゆセ九∴縺ー縲� (1000000000000000128).toFixed(0) 縺� "1000000000000000128" 繧定ソ斐☆荳€譁ケ縺ァ縲� (1000000000000000128).toString() 縺ッ "1000000000000000100" 繧定ソ斐☆縲�

15.7.4.6 Number.prototype.toExponential (fractionDigits)

1 蛟九�謨ー蟄励€∝ー乗焚轤ケ縲� fractionDigits 蛟九�謨ー蟄励↓繧医▲縺ヲ謨ー繧呈欠謨ー陦ィ險倥☆繧区枚蟄怜�繧定ソ斐☆縲� fractionDigits 縺� undefined 縺ェ繧峨�縲∵焚繧剃ク€諢上↓迚ケ螳壹☆繧九�縺ォ蠢�ヲ√→縺吶k縺ョ縺ィ蜷後§譯∵焚繧貞性繧€ (縺薙�蝣エ蜷医€∵焚縺梧欠謨ー陦ィ險倥〒蟶ク縺ォ蜃コ蜉帙&繧後k轤ケ繧帝勁縺� ToString 縺ォ莨シ縺ヲ縺�k)縲� 蜈キ菴鍋噪縺ォ縺ッ縲∵ャ。縺ョ繧ケ繝�ャ繝励r螳溯。後☆繧�:

  1. x 繧偵%縺ョ謨ー蛟、縺ィ縺吶k縲�
  2. f 繧� ToInteger(fractionDigits) 縺ィ縺吶k縲�
  3. x 縺� NaN 縺ェ繧峨�縲∵枚蟄怜� "NaN" 繧定ソ斐☆縲�
  4. s 繧堤ゥコ譁�ュ怜�縺ィ縺吶k縲�
  5. x ≥ 0 縺ェ繧峨�縲� 繧ケ繝�ャ繝� 8 縺ク縲�
  6. s 繧� "-" 縺ィ縺吶k縲�
  7. x = - x 縺ィ縺吶k縲�
  8. x = +∞ 縺ェ繧峨�縲� m = "Infinity" 縺ィ縺励※縲√せ繝�ャ繝� 30 縺ク縲�
  9. fractionDigits 縺� undefined 縺ェ繧峨�縲� 繧ケ繝�ャ繝� 14 縺ク縲�
  10. f < 0 縺セ縺溘� f > 20 縺ェ繧峨�縲� 萓句、� RangeError 繧呈兜縺偵k縲�
  11. x = 0 縺ェ繧峨�縲� 繧ケ繝�ャ繝� 16 縺ク縲�
  12. e 縺ィ n 繧偵€�10fn < 10f+1 縺九▽ 蜴ウ蟇�↑ n × 10e-f - x 縺ョ謨ー蟄ヲ蛟、縺悟庄閭ス縺ェ髯舌j 0 縺ォ謗・霑代☆繧九h縺�↑謨エ謨ー縺ィ縺吶k縲ゅ◎縺ョ繧医≧縺ェ e 縺ィ n 縺ョ邨�′ 2 邨�≠繧九↑繧峨�縲� n × 10e-f 縺悟、ァ縺阪>譁ケ縺ョ e 縺ィ n 繧呈治逕ィ縺吶k縲�
  13. 繧ケ繝�ャ繝� 20 縺ク縲�
  14. x ≠ 0 縺ェ繧峨�縲� 繧ケ繝�ャ繝� 19 縺ク縲�
  15. f = 0 縺ィ縺吶k縲�
  16. m 繧� f+1 蛟九�譁�ュ� '0' 縺ァ讒区�縺輔l繧区枚蟄怜�縺ィ縺吶k縲�
  17. e = 0 縺ィ縺吶k縲�
  18. 繧ケ繝�ャ繝� 21 縺ク縲�
  19. e, n, f 繧偵€� f ≥ 0, 10fn < 10f+1, n × 10e-f 縺ョ謨ー蛟、縺� x, 縺九▽, 蜿ッ閭ス縺ェ髯舌j蟆上&縺� f 縺ァ縺ゅk繧医≧縺ェ謨エ謨ー縺ィ縺吶k縲� n 縺ョ10 騾イ謨ー陦ィ險倥′ f+1 蛟九�謨ー蟄励r謖√▽縺薙→縲� n 縺ッ 10 縺ァ蜑イ繧雁�繧後↑縺�%縺ィ縲� n 縺ョ譛€蟆乗。√�謨ー蟄励�縲√%繧後i縺ョ蛻、螳壼渕貅悶↓繧医▲縺ヲ荳€諢冗噪縺ォ豎コ螳壹&繧後k蠢�ヲ√′縺ェ縺�%縺ィ縺ォ豕ィ諢上€�
  20. m 繧偵€� n 縺ョ 10 騾イ謨ー陦ィ險倥�謨ー蟄励〒讒区�縺輔l繧区枚蟄怜� (鬆�コ上→縺励※ 0 縺ッ蜈郁。後@縺ェ縺�) 縺ィ縺吶k縲�
  21. f = 0 縺ェ繧峨�縲� 繧ケ繝�ャ繝� 24 縺ク縲�
  22. a 繧� m 縺ョ蜈磯�ュ縺ョ譁�ュ励€� b 繧� m 縺ョ谿九j縺ョ f 蛟九�譁�ュ励→縺吶k縲�
  23. m 繧偵€� 3 蛟九�譁�ュ怜� a, ".", b 縺ョ騾」邨舌→縺吶k縲�
  24. e = 0 縺ェ繧峨�縲… = "+" , d = "0" 縺ィ縺励※縲� 繧ケ繝�ャ繝� 29 縺ク縲�
  25. e > 0 縺ェ繧峨�縲… = "+" 縺ィ縺励※縲√せ繝�ャ繝� 28 縺ク縲�
  26. c = "-" 縺ィ縺吶k縲�
  27. e = - e 縺ィ縺吶k縲�
  28. d 繧偵€� e 縺ョ 10 騾イ謨ー陦ィ險倥�謨ー蟄励〒讒区�縺輔l繧区枚蟄怜� (鬆�コ上→縺励※ 0 縺ッ蜈郁。後@縺ェ縺�) 縺ィ縺吶k縲�
  29. m 繧偵€� 4 蛟九�譁�ュ怜� m, "e", c, d 縺ョ騾」邨舌→縺吶k縲�
  30. 譁�ュ怜� s 縺ィ m 縺ョ騾」邨舌r霑斐☆縲�

toExponential 繝。繧ス繝�ラ縺ョ length 繝励Ο繝代ユ繧」縺ッ 1 縺ァ縺ゅk縲�

toExponential 繝。繧ス繝�ラ縺� 2 蛟倶サ・荳翫�蠑墓焚縺ァ蜻シ蜃コ縺輔l繧九↑繧峨�縲√◎縺ョ謖ッ繧玖�縺��譛ェ螳夂セゥ縺ァ縺ゅk (繧サ繧ッ繧キ繝ァ繝ウ 15 蜿ら�)縲�

螳溯」��縲� fractionDigits 縺� 0 繧医j蟆上&縺��エ蜷医€√∪縺� 20 繧医j螟ァ縺阪>蝣エ蜷医� toExponential 縺ョ謖ッ繧玖�縺��諡。蠑オ繧定ィア蜿ッ縺輔l繧九€ゅ%縺ョ蝣エ蜷� toExponential 縺ッ縺昴�蛟、縺ォ萓句、� RangeError 繧呈兜縺偵k蠢�ヲ√�縺ェ縺�€�

NOTE 荳願ィ倥�隕丞援縺ョ隕∵アゅh繧翫b繧医j邊セ蟇�↑蜿悶j豎コ繧√r謠蝉セ帙☆繧句ョ溯」�↓縺、縺�※縺ッ縲√せ繝�ャ繝� 19 縺ョ谺。縺ョ莉」譖ソ繝舌�繧ク繝ァ繝ウ繧偵ぎ繧、繝峨Λ繧、繝ウ縺ィ縺励※逕ィ縺�k縺薙→繧呈耳螂ィ縺吶k:

e, n, f 繧偵€� f ≥ 0, 10fn < 10f+1, n × 10e-f 縺ョ謨ー蛟、縺� x, 縺九▽, 蜿ッ閭ス縺ェ髯舌j蟆上&縺� f 縺ァ縺ゅk繧医≧縺ェ謨エ謨ー縺ィ縺吶k縲り、�焚縺ョ n 縺悟ュ伜惠蜿ッ閭ス縺ァ縺ゅl縺ー縲� n × 10e-f 縺� x 縺ョ蛟、縺ォ譛€繧りソ代>繧医≧縺ェ n 縺ョ蛟、繧帝∈謚槭☆繧九€ょ庄閭ス縺ェ n 縺ョ蛟、縺� 2 蛟九≠繧後�縲∝�謨ー縺ァ縺ゅk譁ケ繧帝∈謚槭☆繧九€�

15.7.4.7 Number.prototype.toPrecision (precision)

1 蛟九�謨ー蟄励€∝ー乗焚轤ケ縲� precision-1 蛟九�謨ー蟄励↓繧医k謖�焚陦ィ險倥€√∪縺溘� precision 譯√�謨ー蟄励↓繧医k蝗コ螳夂せ陦ィ險倥�荳€譁ケ縺ァ縺ゅi繧上&繧後k謨ー繧貞性繧€譁�ュ怜�繧定ソ斐☆縲� precision 縺� undefined 縺ェ繧峨�縲∽サ」繧上j縺ォ ToString (繧サ繧ッ繧キ繝ァ繝ウ 9.8.1) 繧貞他蜃コ縺吶€ょ�菴鍋噪縺ォ縺ッ縲∵ャ。縺ョ繧ケ繝�ャ繝励r螳溯。後☆繧�:

  1. x 繧偵%縺ョ謨ー蛟、縺ィ縺吶k縲�
  2. precision 縺� undefined 縺ェ繧峨�縲� ToString(x) 繧定ソ斐☆縲�
  3. p 繧� ToInteger(precision) 縺ィ縺吶k縲�
  4. x 縺� NaN 縺ェ繧峨�縲� the string "NaN" 繧定ソ斐☆縲�
  5. s 繧堤ゥコ譁�ュ怜�縺ィ縺吶k縲�
  6. x ≥ 0 縺ェ繧峨�縲� 繧ケ繝�ャ繝� 9 縺ク縲�
  7. s 繧� "-" 縺ィ縺吶k縲�
  8. x = - x 縺ィ縺吶k縲�
  9. x = +∞ 縺ェ繧峨�縲� m = "Infinity" 縺ィ縺励※縲√せ繝�ャ繝� 30 縺ク縲�
  10. p < 1 縺セ縺溘� p > 21 縺ェ繧峨�縲� 萓句、� RangeError 繧呈兜縺偵k縲�
  11. x ≠ 0 縺ェ繧峨�縲� 繧ケ繝�ャ繝� 15 縺ク縲�
  12. m 繧� p 蛟九�譁�ュ� '0' 縺ァ讒区�縺輔l繧区枚蟄怜�縺ィ縺吶k縲�
  13. e = 0 縺ィ縺吶k縲�
  14. 繧ケ繝�ャ繝� 18 縺ク縲�
  15. e 縺ィ n 繧偵€� 10p-1 ≤ n < 10p 縺ァ縺ゅj縲√°縺、 n × 10e-p+1 - x 縺ョ蜴ウ蟇�↑謨ー蟄ヲ蛟、縺悟庄閭ス縺ェ髯舌j 0 縺ォ霑代>繧医≧縺ェ謨エ謨ー縺ィ縺吶k縲� e 縺ィ n 縺ョ邨�′ 2 蛟句ュ伜惠縺吶k縺ェ繧峨�縲� n × 10e-p+1 縺悟、ァ縺阪>譁ケ縺ョ e 縺ィ n 繧呈治逕ィ縺吶k縲�
  16. m 繧偵€� n 縺ョ 10 騾イ謨ー陦ィ險倥�謨ー蟄励〒讒区�縺輔l繧区枚蟄怜� (鬆�コ上→縺励※ 0 縺ッ蜈郁。後@縺ェ縺�) 縺ィ縺吶k縲�
  17. e < -6 縺セ縺溘� e ( p 縺ェ繧峨�縲� 繧ケ繝�ャ繝� 22 縺ク縲�
  18. e = p-1 縺ェ繧峨�縲� 繧ケ繝�ャ繝� 30 縺ク縲�
  19. e ≥ 0 縺ェ繧峨�縲� m 繧偵€� m 縺ョ譛€蛻昴� e+1 蛟九�譁�ュ�, 譁�ュ� '.', m 縺ョ谿九j p- (e+1) 蛟九�譁�ュ� 縺ョ騾」邨舌→縺励※縲� 繧ケ繝�ャ繝� 30 縺ク縲�
  20. m 繧呈枚蟄怜� "0.", -(e+1) 蛟九�譁�ュ� '0', 譁�ュ怜� m 縺ョ騾」邨舌→縺吶k縲�
  21. 繧ケ繝�ャ繝� 30 縺ク縲�
  22. a 繧� m 縺ョ譛€蛻昴�譁�ュ励→縺励€� b 繧� m 縺ョ谿九j縺ョ p-1 蛟九�譁�ュ励→縺吶k縲�
  23. m 繧偵€� 3 蛟九�譁�ュ怜� a, ".", b 縺ョ騾」邨舌→縺吶k縲�
  24. e = 0 縺ェ繧峨�縲� c = "+" , d = "0" 縺ィ縺励※縲√せ繝�ャ繝� 29 縺ク縲�
  25. e > 0 縺ェ繧峨�縲� c = "+" 縺ィ縺励※縲√せ繝�ャ繝� 28 縺ク縲�
  26. c = "-" 縺ィ縺吶k縲�
  27. e = - e 縺ィ縺吶k縲�
  28. d 繧偵€� e 縺ョ 10 騾イ謨ー陦ィ險倥�謨ー蟄励〒讒区�縺輔l繧区枚蟄怜� (鬆�コ上→縺励※ 0 縺ッ蜈郁。後@縺ェ縺�) 縺ィ縺吶k縲�
  29. m 繧�4 蛟九�譁�ュ怜� m, "e", c, d 縺ョ騾」邨舌→縺吶k縲�
  30. 譁�ュ怜� s 縺ィ m 縺ョ騾」邨舌r霑斐☆縲�

toPrecision 繝。繧ス繝�ラ縺ョ length 繝励Ο繝代ユ繧」縺ッ 1 縺ァ縺ゅk縲�

toPrecision 繝。繧ス繝�ラ縺� 2 蛟倶サ・荳翫�蠑墓焚縺ァ蜻シ蜃コ縺輔l繧九↑繧峨�縲√◎縺ョ謖ッ繧玖�縺��譛ェ螳夂セゥ縺ァ縺ゅk (繧サ繧ッ繧キ繝ァ繝ウ 15 蜿ら�)縲�

螳溯」��縲� precision 縺ョ蛟、縺� 0 繧医j蟆上&縺��エ蜷医€√∪縺� 21 繧医j螟ァ縺阪>蝣エ蜷医� toPrecision 縺ョ謖ッ繧玖�縺��諡。蠑オ繧定ィア蜿ッ縺輔l繧九€ゅ%縺ョ蝣エ蜷� toPrecision 縺ッ縺昴�蛟、縺ォ萓句、� RangeError 繧呈兜縺偵k蠢�ヲ√�縺ェ縺�€�

15.7.5 Number 繧、繝ウ繧ケ繧ソ繝ウ繧ケ縺ョ繝励Ο繝代ユ繧」 (Properties of Number Instances)

Number 繧、繝ウ繧ケ繧ソ繝ウ繧ケ縺ッ縲¨umber 繝励Ο繝医ち繧、繝励が繝悶ず繧ァ繧ッ繝医°繧臥カ呎価縺吶k繝励Ο繝代ユ繧」縺ョ荳翫↓迚ケ縺ォ繝励Ο繝代ユ繧」繧呈戟縺溘↑縺�€�

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