javascript - 计算一个人的年龄有多少天？

Question

我需要计算出某人有多少天了，但我不确定数学。这是我到目前为止所拥有的:

var birthYear = parseInt(prompt ('Enter your birth year:'));
var birthMonth = prompt ('Enter the name of the month of birth:');
var birthDay = parseInt(prompt ('Enter your day of birth as an integer:'));
var milliDay = 1000*60*60*24; //Milliseconds in a day
monthAbb = 'janfebmaraprmayjunjulaugsepoctnovdec';
chineseZod = 12;
zodCycle = 1924; //Chinese Zodiac Cycle
var zodAnimal = new Array('Rat','Ox','Tiger','Rabbit','Dragon','Snake','Horse','Goat','Monkey','Rooster','Dog','Pig');
var zodAnimalD = new Array('Forthright, tenacious, intense, meticulous, charismatic, sensitive, intellectual, industrious, charming, eloquent, sociable, artistic, and shrewd.  Can be manipulative, vindictive, self-destructive, envious, mendacious, venal, obstinate, critical, over-ambitious, ruthless, intolerant, and scheming.','Dependable, ambitious, calm, methodical, born leader, patient, hardworking, conventional, steady, modest, logical, resolute, and tenacious.  Can be stubborn, dogmatic, hot-tempered, narrow-minded, materialistic, rigid, and demanding.','Unpredictable, rebellious, colorful, powerful, passionate, daring, impulsive, vigorous, stimulating, sincere, affectionate, humanitarian, and generous.  Can be restless, reckless, impatient, quick-tempered, obstinate, selfish, aggressive, and moody.','Gracious, good friend, kind, sensitive, soft-spoken, amiable, elegant, reserved, cautious, artistic, thorough, tender, self-assured, shy, astute, compassionate, lucky, and flexible.  Can be moody, detached, superficial, self-indulgent, opportunistic, and stubborn.','Magnanimous, stately, vigorous, strong, self-assured, proud, noble, direct, dignified, eccentric, intellectual, fiery, passionate, decisive, pioneering, artistic, generous, and loyal.  Can be tactless, arrogant, imperious, tyrannical, demanding, intolerant, dogmatic, violent, impetuous, and brash.','Deep thinker, wise, mystic, graceful, soft-spoken, sensual, creative, prudent, shrewd, elegant, cautious, responsible, calm, strong, constant, and purposeful.  Can be a loner, bad communicator, possessive, hedonistic, self-doubting, distrustful, mendacious, suffocating, and cold.','Cheerful, popular, quick-witted, changeable, earthy, perceptive, talkative, agile, magnetic, intelligent, astute, flexible, and open-minded.  Can be fickle, arrogant, childish, anxious, rude, gullible, and stubborn.','Righteous, sincere, sympathetic, mild-mannered, observant, artistic, intellectual, ingenious, innovative, creative, mothering, peaceful, and generous.  Can be indecisive, over-passive, worrier, pessimistic, sensitive, shy, and weak-willed.','Inventor, motivator, improviser, quick-witted, inquisitive, flexible, innovative, problem solver, self-assured, sociable, artistic, polite, dignified, competitive, objective, and factual.  Can be egotistical, vain, arrogant, selfish, reckless, snobbish, deceptive, manipulative, cunning, jealous, suspicious, and stubborn.','  Acute, neat, meticulous, organized, self-assured, decisive, conservative, critical, perfectionist, alert, zealous, practical, scientific, and responsible.  Can be over zealous and critical, puritanical, egotistical, abrasive, proud, opinionated, and gives into empty bravado.','Honest, intelligent, straightforward, loyal, sense of justice and fair play, attractive, amicable, unpretentious, sociable, open-minded, idealistic, moralistic, practical, affectionate, sensitive, and easy going.  Can be cynical, lazy, cold, judgmental, pessimistic, worrier, stubborn, and quarrelsome.','Honest, gallant, sturdy, sociable, peace-loving, patient, loyal, hard-working, trusting, sincere, calm, understanding, thoughtful, scrupulous, passionate, and intelligent.  Can be naive, over-reliant, self-indulgent, gullible, fatalistic, and materialistic.');
var monthArr = new Array(11);

monthArr [0] = "jan";
monthArr [1] = "feb";
monthArr [2] = "mar";
monthArr [3] = "apr";
monthArr [4] = "may";
monthArr [5] = "jun";
monthArr [6] = "jul";
monthArr [7] = "aug";
monthArr [8] = "sep";
monthArr [9] = "oct";
monthArr [10] = "nov";
monthArr [11] = "dec";

var monthNum = monthAbb.indexOf(birthMonth.slice(0, 3).toLowerCase()) / 3; 
alert(monthNum);
var d = new Date (birthYear, monthNum, birthDay);
alert(d);
var dCurrent = new Date();
dCurrent = dCurrent.getTime(); //Grabs the time of the current date in milliseconds.
var dTotal = dCurrent - d;
alert(dTotal);
dTotal = dTotal / milliDay;
dTotal = Math.floor(dTotal); //7193
alert(dTotal + ' is after division');
dTotal = dTotal / 365.25;
dTotal = Math.floor(dTotal);
alert(dTotal + ' is how old you are!');
dTotal = birthYear - zodCycle;
dTotal = dTotal % chineseZod;
alert(dTotal);
alert(d);
var testS;
testS = dCurrent - d;
testS = testS / milliDay;
testS = testS * 365.25;
document.write("<span style=\"color: red;\">" + 'Your birthday is ' + d.toDateString() + "</span>");
alert(testS);

Answer 1

这实际上比那容易得多。一旦你有了两个日期(他们的生日和“现在”)，你只需执行以下操作:

var days = Math.floor((now - birthDate) / 86400000);

这是因为在 JavaScript 中，Date objects自纪元以来以毫秒为单位的保持时间，当您对它们进行数学计算时，它们使用该毫秒值(结果是毫秒数)。 JavaScript 假设每天恰好有 86,400,000 毫秒。

因此，一旦您有了 birthYear、monthNum 和 birthDay:

var birthDate = new Date(birthYear, monthNum, birthDay);
var days = Math.floor((new Date() - birthdate) / 86400000);

Live example using a datepicker | source