问题
I would like to format my numbers to always display 2 decimal places, rounding where applicable.
Examples:
number display
------ -------
1 1.00
1.341 1.34
1.345 1.35
I have been using this:
parseFloat(num).toFixed(2);
But it\'s displaying 1 as 1, rather than 1.00.
回答1:
This works fine in FF4:
parseFloat(Math.round(num3 * 100) / 100).toFixed(2);
Live Demo
var num1 = "1";
document.getElementById('num1').innerHTML = parseFloat(Math.round(num1 * 100) / 100).toFixed(2);
var num2 = "1.341";
document.getElementById('num2').innerHTML = parseFloat(Math.round(num2 * 100) / 100).toFixed(2);
var num3 = "1.345";
document.getElementById('num3').innerHTML = parseFloat(Math.round(num3 * 100) / 100).toFixed(2);span {
border: 1px solid #000;
margin: 5px;
padding: 5px;
}<span id="num1"></span>
<span id="num2"></span>
<span id="num3"></span>Note that it will round to 2 decimal places, so the input 1.346 will return 1.35.
回答2:
Number(1).toFixed(2); // 1.00
Number(1.341).toFixed(2); // 1.34
Number(1.345).toFixed(2); // 1.34 NOTE: See andy's comment below.
Number(1.3450001).toFixed(2); // 1.35
document.getElementById('line1').innerHTML = Number(1).toFixed(2);
document.getElementById('line2').innerHTML = Number(1.341).toFixed(2);
document.getElementById('line3').innerHTML = Number(1.345).toFixed(2);
document.getElementById('line4').innerHTML = Number(1.3450001).toFixed(2);<span id="line1"></span>
<br/>
<span id="line2"></span>
<br/>
<span id="line3"></span>
<br/>
<span id="line4"></span>回答3:
This answer will fail if value = 1.005.
As a better solution, the rounding problem can be avoided by using numbers represented in exponential notation:
Number(Math.round(1.005+'e2')+'e-2'); // 1.01
Cleaner code as suggested by @Kon, and the original author:
Number(Math.round(parseFloat(value + 'e' + decimalPlaces)) + 'e-' + decimalPlaces)
You may add toFixed() at the end to retain the decimal point e.g: 1.00 but note that it will return as string.
Number(Math.round(parseFloat(value + 'e' + decimalPlaces)) + 'e-' + decimalPlaces).toFixed(decimalPlaces)
Credit: Rounding Decimals in JavaScript
回答4:
var num = new Number(14.12);
console.log(num.toPrecision(2));//outputs 14
console.log(num.toPrecision(3));//outputs 14.1
console.log(num.toPrecision(4));//outputs 14.12
console.log(num.toPrecision(5));//outputs 14.120
回答5:
A much more generic solution for rounding to N places
function roundN(num,n){
return parseFloat(Math.round(num * Math.pow(10, n)) /Math.pow(10,n)).toFixed(n);
}
console.log(roundN(1,2))
console.log(roundN(1.34,2))
console.log(roundN(1.35,2))
console.log(roundN(1.344,2))
console.log(roundN(1.345,2))
console.log(roundN(1.344,3))
console.log(roundN(1.345,3))
console.log(roundN(1.3444,3))
console.log(roundN(1.3455,3))
Output
1.00
1.34
1.35
1.34
1.35
1.344
1.345
1.344
1.346
回答6:
Simplest answer:
var num = 1.2353453;
num.toFixed(2); // 1.24
Example: http://jsfiddle.net/E2XU7/
回答7:
For the most accurate rounding, create this function:
function round(value, decimals) {
return Number(Math.round(value +'e'+ decimals) +'e-'+ decimals).toFixed(decimals);
}
and use it to round to 2 decimal places:
console.log("seeked to " + round(1.005, 2));
> 1.01
Thanks to Razu, this article, and MDN's Math.round reference.
回答8:
var number = 123456.789;
console.log(new Intl.NumberFormat('en-IN', { maximumFractionDigits: 2 }).format(number));
https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/NumberFormat
回答9:
If you're already using jQuery, you could look at using the jQuery Number Format plugin.
The plugin can return formatted numbers as a string, you can set decimal, and thousands separators, and you can choose the number of decimals to show.
$.number( 123, 2 ); // Returns '123.00'
You can also get jQuery Number Format from GitHub.
回答10:
Is this what you mean?
function showAsFloat(num, n){
return !isNaN(+num) ? (+num).toFixed(n || 2) : num;
}
document.querySelector('#result').textContent =
[
'command | result',
'-----------------------------------------------',
'showAsFloat(1); | ' + showAsFloat(1),
'showAsFloat(1.314); | ' + showAsFloat(1.314),
'showAsFloat(\'notanumber\') | ' + showAsFloat('notanumber'),
'showAsFloat(\'23.44567\', 3) | ' + showAsFloat('23.44567', 3),
'showAsFloat(2456198, 5) | ' + showAsFloat('2456198', 5),
'showAsFloat(0); | ' + showAsFloat(0)
].join('\n');<pre id="result"></pre>回答11:
Convert a number into a string, keeping only two decimals:
var num = 5.56789;
var n = num.toFixed(2);
The result of n will be:
5.57
回答12:
Are you looking for floor?
var num = 1.42482;
var num2 = 1;
var fnum = Math.floor(num).toFixed(2);
var fnum2 = Math.floor(num2).toFixed(2);
alert(fnum + " and " + fnum2); //both values will be 1.00
回答13:
For modern browsers, use toLocaleString:
var num = 1.345;
num.toLocaleString(undefined, { maximumFractionDigits: 2, minimumFractionDigits: 2 });
Specify a locale tag as first parameter to control the decimal separator. For a dot, use for example English U.S. locale:
num.toLocaleString("en-US", { maximumFractionDigits: 2, minimumFractionDigits: 2 });
which gives:
1.35
Most countries in Europe use a comma as decimal separator, so if you for example use Swedish/Sweden locale:
num.toLocaleString("sv-SE", { maximumFractionDigits: 2, minimumFractionDigits: 2 });
it will give:
1,35
回答14:
function currencyFormat (num) {
return "$" + num.toFixed(2).replace(/(\d)(?=(\d{3})+(?!\d))/g, "$1,")
}
console.info(currencyFormat(2665)); // $2,665.00
console.info(currencyFormat(102665)); // $102,665.00
回答15:
Here's also a generic function that can format to any number of decimal places:
function numberFormat(val, decimalPlaces) {
var multiplier = Math.pow(10, decimalPlaces);
return (Math.round(val * multiplier) / multiplier).toFixed(decimalPlaces);
}
回答16:
Where specific formatting is required, you should write your own routine or use a library function that does what you need. The basic ECMAScript functionality is usually insufficient for displaying formatted numbers.
A thorough explanation of rounding and formatting is here: http://www.merlyn.demon.co.uk/js-round.htm#RiJ
As a general rule, rounding and formatting should only be peformed as a last step before output. Doing so earlier may introduce unexpectedly large errors and destroy the formatting.
回答17:
function number_format(string,decimals=2,decimal=',',thousands='.',pre='R$ ',pos=' Reais'){
var numbers = string.toString().match(/\d+/g).join([]);
numbers = numbers.padStart(decimals+1, "0");
var splitNumbers = numbers.split("").reverse();
var mask = '';
splitNumbers.forEach(function(d,i){
if (i == decimals) { mask = decimal + mask; }
if (i>(decimals+1) && ((i-2)%(decimals+1))==0) { mask = thousands + mask; }
mask = d + mask;
});
return pre + mask + pos;
}
var element = document.getElementById("format");
var money= number_format("10987654321",2,',','.');
element.innerHTML = money;#format{
display:inline-block;
padding:10px;
border:1px solid #ddd;
background:#f5f5f5;
}<div id='format'>Test 123456789</div>回答18:
You are not giving us the whole picture.
javascript:alert(parseFloat(1).toFixed(2)) shows 1.00 in my browsers when I paste it int0 the location bar.
However if you do something to it afterwards, it will revert.
var num = 2
document.getElementById('spanId').innerHTML=(parseFloat(num).toFixed(2)-1)
shows 1 and not 1.00
回答19:
var quantity = 12;
var import1 = 12.55;
var total = quantity * import1;
var answer = parseFloat(total).toFixed(2);
document.write(answer);
回答20:
I had to decide between the parseFloat() and Number() conversions before I could make toFixed() call. Here's an example of a number formatting post-capturing user input.
HTML:
<input type="number" class="dec-number" min="0" step="0.01" />
Event handler:
$('.dec-number').on('change', function () {
const value = $(this).val();
$(this).val(value.toFixed(2));
});
The above code will result in TypeError exception. Note that although the html input type is "number", the user input is actually a "string" data type. However, toFixed() function may only be invoked on an object that is a Number.
My final code would look as follows:
$('.dec-number').on('change', function () {
const value = Number($(this).val());
$(this).val(value.toFixed(2));
});
The reason I favor to cast with Number() vs. parseFloat() is because I don't have to perform an extra validation neither for an empty input string, nor NaN value. The Number() function would automatically handle an empty string and covert it to zero.
回答21:
Just run into this one of longest thread, below is my solution:
parseFloat(Math.round((parseFloat(num * 100)).toFixed(2)) / 100 ).toFixed(2)
Let me know if anyone can poke a hole
回答22:
I do like:
var num = 12.749;
parseFloat((Math.round(num * 100) / 100).toFixed(2)); // 123.75
Round the number with 2 decimal points,
then make sure to parse it with parseFloat()
to return Number, not String unless you don't care if it is String or Number.
回答23:
Extend Math object with precision method
Object.defineProperty(Math, 'precision',{
value: function (value,precision,type){
var v = parseFloat(value),
p = Math.max(precision,0)||0,
t = type||'round';
return (Math[t](v*Math.pow(10,p))/Math.pow(10,p)).toFixed(p);
}
});
console.log(
Math.precision(3.1,3), // round 3 digits
Math.precision(0.12345,2,'ceil'), // ceil 2 digits
Math.precision(1.1) // integer part
)回答24:
parseInt(number * 100) / 100; worked for me.
回答25:
here is another solution to round only using floor, meaning, making sure calculated amount won't be bigger than the original amount (sometimes needed for transactions):
Math.floor(num* 100 )/100;
回答26:
function numberWithCommas(number) {
var newval = parseFloat(Math.round(number * 100) / 100).toFixed(2);
return newval.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");
}
回答27:
You can try this code:
function FormatNumber(number, numberOfDigits = 2) {
try {
return new Intl.NumberFormat('en-US').format(parseFloat(number).toFixed(2));
} catch (error) {
return 0;
}
}
var test1 = FormatNumber('1000000.4444');
alert(test1); // 1,000,000.44
var test2 = FormatNumber(100000000000.55555555, 4);
alert(test2); // 100,000,000,000.56
回答28:
(num + "").replace(/^([0-9]*)(\.[0-9]{1,2})?.*$/,"$1$2")
回答29:
This is how I solve my problem:
parseFloat(parseFloat(floatString).toFixed(2));
来源：https://stackoverflow.com/questions/6134039/format-number-to-always-show-2-decimal-places