How can I calculate the age of a person in Javascript from the date of birth?
I tried something like:
function idade(dia, mes, ano) {
return new Date().getFullYear() - ano;
}
idade(11, 12, 1980); // 33
idade(15, 2, 2011); // 2
idade(5, 31, 1993); // 20
- Pedro : Hi, Maria. How old are you?
- Maria : Pedro, I was born on February 28, 1990.
- Pedro : So, I already know how old you are!
- Maria : What is it?
- Pedro : Just pick up the current year and subtract for the year you were born. Soon, 2014 - 1990 = 24. You are 24 years old.
- Maria : No, actually I'm 23 years old. I do 24 February 28th.
- Maria : To calculate age, you subtract the current year by the year of birth. But if you have not yet passed the anniversary date, you subtract 1.
- Peter : Ah, yeah. I forgot that!
function idade(ano_aniversario, mes_aniversario, dia_aniversario) {
var d = new Date,
ano_atual = d.getFullYear(),
mes_atual = d.getMonth() + 1,
dia_atual = d.getDate(),
ano_aniversario = +ano_aniversario,
mes_aniversario = +mes_aniversario,
dia_aniversario = +dia_aniversario,
quantos_anos = ano_atual - ano_aniversario;
if (mes_atual < mes_aniversario || mes_atual == mes_aniversario && dia_atual < dia_aniversario) {
quantos_anos--;
}
return quantos_anos < 0 ? 0 : quantos_anos;
}
console.log(idade(1980, 12, 11)); // 33
console.log(idade(2011, 2, 15)); // 2
console.log(idade(1993, 31, 5)); // 20
I suggest comparing the month and day of the month: if today's date is greater than or equal to birth (i.e. birthday is over), then just make the difference between years. Otherwise, make a difference and subtract 1 :
function idade(nascimento, hoje) {
var diferencaAnos = hoje.getFullYear() - nascimento.getFullYear();
if ( new Date(hoje.getFullYear(), hoje.getMonth(), hoje.getDate()) <
new Date(hoje.getFullYear(), nascimento.getMonth(), nascimento.getDate()) )
diferencaAnos--;
return diferencaAnos;
}
A one-line solution, calculating from the number of days:
// calcula a idade considerando os parâmetros
// 'nascimento' e 'hoje' como objetos Date
function calculaIdade(nascimento, hoje){
return Math.floor(Math.ceil(Math.abs(nascimento.getTime() - hoje.getTime()) / (1000 * 3600 * 24)) / 365.25);
}
The logic used is as follows:
Math.abs(nascimento.getTime() - hoje.getTime()) - returns the amount of milliseconds passed from nascimento to hoje . The Math.abs function returns the subtraction module, that is, it turns a negative number into a positive one and keeps the signal a positive one. / (1000 * 3600 * 24) - calculates the number of days from the amount of milliseconds returned in the previous expression. Dividing by 1000, we have the amount of seconds; the number of seconds divided by 3600 we have the amount of hours (because in 1 hour 3600 seconds fit); and finally divide the amount of hours by 24, which will have the corresponding amount of days. Math.ceil - rounds up the decimal value of the previous operation, since it is considered that a day has passed even though the number of hours does not give 24 hours. Like for example a baby born last night, we consider that today morning has already 1 day of life. / 365.25 - finally, we calculate the year by dividing the total days by the total of days that fit in a year. The number 365.25 is because a year has approximately 365 days and 6 hours, which equals 365.25 days. The bixesto year comes from this difference, because every 4 years, the 6 hours disregarded in the calendar become 24 hours, that is another day. Math.floor - rounds down the amount of years. Well, it does not matter if the person celebrates his birthday tomorrow and he's 25,999 years old, he's 25 years old. How about calculating in a much more minimalist way? The calculation with ms is highly superior considering the performance. Ex: I was born on 12/17/1995. Then:
function calcAge(dateString) {
var birthday = +new Date(dateString);
return ~~((Date.now() - birthday) / (31557600000));
}
console.log(calcAge("Thu Dec 17 1995 00:51:54 GMT-0300 (BRT)"));The technique used can be found in: link And I thank Caio Ribeiro for showing me
Hello, I've adapted the @Gabriel S. code to accept date in the Brazilian standard.
function calcIdade(data) {
var d = new Date,
ano_atual = d.getFullYear(),
mes_atual = d.getMonth() + 1,
dia_atual = d.getDate(),
split = data.split('/'),
novadata = split[1] + "/" +split[0]+"/"+split[2],
data_americana = new Date(novadata),
vAno = data_americana.getFullYear(),
vMes = data_americana.getMonth() + 1,
vDia = data_americana.getDate(),
ano_aniversario = +vAno,
mes_aniversario = +vMes,
dia_aniversario = +vDia,
quantos_anos = ano_atual - ano_aniversario;
if (mes_atual < mes_aniversario || mes_atual == mes_aniversario && dia_atual < dia_aniversario) {
quantos_anos--;
}
return quantos_anos < 0 ? 0 : quantos_anos;
}
// calcIdade('02/01/1978') => 39
// calcIdade('03/09/1980') => 36