Rounding a number to two decimals sounds like a simple problem but it was a challenge when using the previous built-in functions. The good news is that now we have a better correct solution. toFixedHi, Saya masih newbie dalam javascript, jadi mohon bantuan teman" disini dg harapan bisa membantu saya. bagaimana cara saya membuat kondisi dalam javascript, jika input absen < 0 maka kolom 'na' otomatis 0, jika > 5 maka kolom na lakukan kalkulasi sesuai nilai yg dimasukkan. Berikut kode saya function hitung2() { console.log('test'); var g = $("#jml_hadir").val(); var a = $("#t1").val(); var b = $("#t2").val(); var c = $("#t3").val(); nt = (parseFloat(a) + parseFloat(b) + parseFloat(c)) /3; nt = nt.toFixed(2); $("#nt").val(nt); var d = $("#nt").val(); var e = $("#np").val(); th = (parseFloat(g)); $("#th").val(th); if (th<5) { f = 0; $("input[name=na]").val(f); }else{ var f = (parseFloat(e)*3 + parseFloat(d)*7) /10 ; f = f.toFixed(2); $("input[name=na]").val(f);} } Mohon bantuannya ya :) @warnamagenta 13 Kontribusi 0 Poin Dipost: 4 tahun yang lalu Update 2 tahun yang lalu
Jawaban Terpilih Maaf banget baru login kembali dan lihat pertanyaan ini lupa dijawab. Ini hasil perhitungan gw var g = $("#jml_hadir").val(); var a = $("#t1").val(); var b = $("#t2").val(); var c = $("#t3").val(); nt = (parseFloat(a) + parseFloat(b) + parseFloat(c)) /3; nt = ntt.toFixed(2); $("#nt").val(nt); var d = $("#nt").val(); var e = $("#np").val(); th = (parseFloat(g)); $("#th").val(th); if (th<5) { f = 0; $("input[name=nat]").val(f); }else{ var f = (parseFloat(e)*3 + parseFloat(d)*7) /10 ; f = f.toFixed(2); $("input[name=nat]").val(f);} @warnamagenta 13 Kontribusi 0 Poin Dipost: 3 tahun yang lalu Update 3 tahun yang lalu Jawabancode diatas kendalanya apa gan? @dianarifr 642 Kontribusi 316 Poin Dipost: 4 tahun yang lalu Kalau liat dari code nya seharusnya sudah jalan itu , bisa di lengkapin gan biar mastah2 disini bisa pada bantuin ^^ @markeronly 378 Kontribusi 230 Poin Dipost: 4 tahun yang lalu Maaf banget baru login kembali dan lihat pertanyaan ini lupa dijawab. Ini hasil perhitungan gw var g = $("#jml_hadir").val(); var a = $("#t1").val(); var b = $("#t2").val(); var c = $("#t3").val(); nt = (parseFloat(a) + parseFloat(b) + parseFloat(c)) /3; nt = ntt.toFixed(2); $("#nt").val(nt); var d = $("#nt").val(); var e = $("#np").val(); th = (parseFloat(g)); $("#th").val(th); if (th<5) { f = 0; $("input[name=nat]").val(f); }else{ var f = (parseFloat(e)*3 + parseFloat(d)*7) /10 ; f = f.toFixed(2); $("input[name=nat]").val(f);} @warnamagenta 13 Kontribusi 0 Poin Dipost: 3 tahun yang lalu Update 3 tahun yang lalu Login untuk gabung berdiskusi In modern JavaScript, there are two types of numbers:
So here we’ll talk about regular numbers. Let’s expand our knowledge of them. More ways to write a numberImagine we need to write 1 billion. The obvious way is:
We also can use underscore
Here the underscore In real life though, we try to avoid writing long sequences of zeroes. We’re too lazy for that. We’ll try to write something like In JavaScript,
we can shorten a number by appending the letter
In other words,
Now let’s write something very small. Say, 1 microsecond (one millionth of a second): Just like before, using
If we count the zeroes in In other words, a negative number after
Hex, binary and octal numbersHexadecimal numbers are widely used in JavaScript to represent colors, encode characters, and for many other things. So naturally, there exists a shorter way to write them: For instance:
Binary and octal numeral systems are rarely used, but also supported using the
There are only 3 numeral systems with such support. For other numeral systems, we should use the function toString(base)The
method For example:
The Common use cases for this are:
Two dots to call a method Please note that two dots in If we placed a single dot: Also could write RoundingOne of the most used operations when working with numbers is rounding. There are several built-in functions for rounding: Math.floor Rounds down: 3.1 becomes 3 , and -1.1 becomes -2 .Math.ceil Rounds up: 3.1 becomes 4 , and -1.1 becomes -1 .Math.round Rounds
to the nearest integer: 3.1 becomes 3 , 3.6 becomes 4 , the middle case: 3.5 rounds up to 4 too.Math.trunc (not supported by Internet Explorer)Removes anything after the decimal point without rounding: 3.1 becomes 3 , -1.1 becomes -1 .Here’s the table to summarize the differences between them:
These functions cover all of the possible ways to deal with the decimal part of a number. But what if we’d like to round the number to For instance, we have There are two ways to do so:
Imprecise calculationsInternally, a number is represented in 64-bit format IEEE-754, so there are exactly 64 bits to store a number: 52 of them are used to store the digits, 11 of them store the position of the decimal point, and 1 bit is for the sign. If a number is really huge, it may overflow the
64-bit storage and become a special numeric value
What may be a little less obvious, but happens quite often, is the loss of precision. Consider this (falsy!) equality test:
That’s right, if we check whether the sum of Strange! What is it then if not
Ouch! Imagine you’re making an e-shopping site and the visitor puts But why does this happen? A number is stored in memory in its binary form, a sequence of bits – ones and zeroes. But fractions like What is So, division by powers There’s just no way to store exactly 0.1 or exactly 0.2 using the binary system, just like there is no way to store one-third as a decimal fraction. The numeric format IEEE-754 solves this by rounding to the nearest possible number. These rounding rules normally don’t allow us to see that “tiny precision loss”, but it exists. We can see this in action:
And when we sum two numbers, their “precision losses” add up. That’s why Not only JavaScript The same issue exists in many other programming languages. PHP, Java, C, Perl, Ruby give exactly the same result, because they are based on the same numeric format. Can we work around the problem? Sure, the most reliable method is to round the result with the help of a method toFixed(n):
Please note that
We also can temporarily multiply the numbers by 100 (or a bigger number) to turn them into integers, do the maths, and then divide back. Then, as we’re doing maths with integers, the error somewhat decreases, but we still get it on division:
So, multiply/divide approach reduces the error, but doesn’t remove it totally. Sometimes we could try to evade fractions at all. Like if we’re dealing with a shop, then we can store prices in cents instead of dollars. But what if we apply a discount of 30%? In practice, totally evading fractions is rarely possible. Just round them to cut “tails” when needed. The funny thing Try running this:
This suffers from the same issue: a loss of precision. There are 64 bits for the number, 52 of them can be used to store digits, but that’s not enough. So the least significant digits disappear. JavaScript doesn’t trigger an error in such events. It does its best to fit the number into the desired format, but unfortunately, this format is not big enough. Two zeroes Another funny consequence of the internal representation of numbers is the existence of two zeroes: That’s because a sign is represented by a single bit, so it can be set or not set for any number including a zero. In most cases the distinction is unnoticeable, because operators are suited to treat them as the same. Tests: isFinite and isNaNRemember these two special numeric values?
They belong to the type
Sometimes
Please note that an empty or a space-only string is treated as
Number.isNaN and Number.isFinite methods are the more “strict” versions of
In a
way, Comparison with There is a special built-in method
In all other cases, We mention parseInt and parseFloatNumeric conversion using a plus
The sole exception is spaces at the beginning or at the end of the string, as they are ignored. But in real life we often have values in units, like
That’s what They “read” a number from a string until they can’t. In case of an error, the gathered number is returned. The function
There
are situations when
The second argument of The
Other math functionsJavaScript has a built-in Math object which contains a small library of mathematical functions and constants. A few examples: Math.random() Returns a random number from 0 to 1 (not including 1).
Math.max(a, b, c...) and Math.min(a, b, c...) Returns the greatest and smallest from the arbitrary number of arguments.
Math.pow(n, power) Returns
There are more functions and constants in SummaryTo write numbers with many zeroes:
For different numeral systems:
For regular number tests:
For converting values like
For fractions:
More mathematical functions:
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