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fix(formatNumber): cope with large and small number corner cases
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By manually parsing and rounding we can deal with the more tricky numbers

Closes angular#13394
Closes angular#8674
Closes angular#12709
Closes angular#8705
Closes angular#12707
Closes angular#10246
Closes angular#10252
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@petebacondarwin
petebacondarwin committed Dec 1, 2015
1 parent 08c9a5e commit 6a0686d
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243 changes: 173 additions & 70 deletions src/ng/filter/filters.js
View file
Original file line number Diff line number Diff line change
@@ -1,5 +1,9 @@
'use strict';

var MAX_DIGITS = 22;
var DECIMAL_SEP = '.';
var ZERO_CHAR = '0';

/**
* @ngdoc filter
* @name currency
Expand Down Expand Up @@ -124,8 +128,6 @@ function currencyFilter($locale) {
</file>
</example>
*/


numberFilter.$inject = ['$locale'];
function numberFilter($locale) {
var formats = $locale.NUMBER_FORMATS;
Expand All @@ -139,93 +141,194 @@ function numberFilter($locale) {
};
}

var DECIMAL_SEP = '.';
function formatNumber(number, pattern, groupSep, decimalSep, fractionSize) {
if (isObject(number)) return '';
/**
* Parse a number (as a string) into three components that can be used
* for formatting the number.
*
* (Significant bits of this parse algorithm came from https://github.com/MikeMcl/big.js/)
*
* @param {string} numStr The number to parse
* @return {object} An object describing this number, containing the following keys:
* - d : an array of digits containing leading zeros as necessary
* - i : the number of the digits in `d` that are to the left of the decimal point
* - e : the exponent for numbers that would need more than `MAX_DIGITS` digits in `d`
*
*/
function parse(numStr) {
var exponent = 0, digits, numberOfIntegerDigits;
var i, j, zeros;

// Decimal point?
if ((numberOfIntegerDigits = numStr.indexOf(DECIMAL_SEP)) > -1) {
numStr = numStr.replace(DECIMAL_SEP, '');
}

var isNegative = number < 0;
number = Math.abs(number);
// Exponential form?
if ((i = numStr.search(/e/i)) > 0) {
// Work out the exponent.
if (numberOfIntegerDigits < 0) numberOfIntegerDigits = i;
numberOfIntegerDigits += +numStr.slice(i + 1);
numStr = numStr.substring(0, i);
} else if (numberOfIntegerDigits < 0) {
// There was no decimal point or exponent so it is an integer.
numberOfIntegerDigits = numStr.length;
}

var isInfinity = number === Infinity;
if (!isInfinity && !isFinite(number)) return '';
// Count the number of leading zeros.
for (i = 0; numStr.charAt(i) == ZERO_CHAR; i++);

var numStr = number + '',
formatedText = '',
hasExponent = false,
parts = [];
if (i == (zeros = numStr.length)) {
// The digits are all zero.
digits = [0];
numberOfIntegerDigits = 1;
} else {
// Count the number of trailing zeros
zeros--;
while (numStr.charAt(zeros) == ZERO_CHAR) zeros--;

// Trailing zeros are insignificant so ignore them
numberOfIntegerDigits -= i;
digits = [];
// Convert string to array of digits without leading/trailing zeros.
for (j = 0; i <= zeros; i++, j++) {
digits[j] = +numStr.charAt(i);
}
}

if (isInfinity) formatedText = '\u221e';
// If the number overflows the maximum allowed digits then use an exponent.
if (numberOfIntegerDigits > MAX_DIGITS) {
digits = digits.splice(0, MAX_DIGITS - 1);
exponent = numberOfIntegerDigits - 1;
numberOfIntegerDigits = 1;
}

return { d: digits, e: exponent, i: numberOfIntegerDigits };
}

if (!isInfinity && numStr.indexOf('e') !== -1) {
var match = numStr.match(/([\d\.]+)e(-?)(\d+)/);
if (match && match[2] == '-' && match[3] > fractionSize + 1) {
number = 0;
/**
* Round the parsed number to the specified number of decimal places
* This function changed the parsedNumber in-place
*/
function roundNumber(parsedNumber, fractionSize, minFrac, maxFrac) {
var digits = parsedNumber.d;
var fractionLen = digits.length - parsedNumber.i;

// determine fractionSize if it is not specified; `+fractionSize` converts it to a number
fractionSize = (isUndefined(fractionSize)) ? Math.min(Math.max(minFrac, fractionLen), maxFrac) : +fractionSize;

// The index of the digit to where rounding is to occur
var roundAt = fractionSize + parsedNumber.i;
var digit = digits[roundAt];

if (roundAt > 0) {
digits.splice(roundAt);
} else {
formatedText = numStr;
hasExponent = true;
// We rounded to zero so reset the parsedNumber
parsedNumber.i = 1;
digits.length = roundAt = fractionSize + 1;
for (var i=0; i < roundAt; i++) digits[i] = 0;
}
}

if (!isInfinity && !hasExponent) {
var fractionLen = (numStr.split(DECIMAL_SEP)[1] || '').length;
if (digit >= 5) digits[roundAt - 1]++;

// determine fractionSize if it is not specified
if (isUndefined(fractionSize)) {
fractionSize = Math.min(Math.max(pattern.minFrac, fractionLen), pattern.maxFrac);
// Pad out with zeros to get the required fraction length
for (; fractionLen < fractionSize; fractionLen++) digits.push(0);


// Do any carrying, e.g. a digit was rounded up to 10
var carry = digits.reduceRight(function(carry, d, i, digits) {
d = d + carry;
digits[i] = d % 10;
return Math.floor(d / 10);
}, 0);
if (carry) {
digits.unshift(carry);
parsedNumber.i++;
}
}

// safely round numbers in JS without hitting imprecisions of floating-point arithmetics
// inspired by:
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/round
number = +(Math.round(+(number.toString() + 'e' + fractionSize)).toString() + 'e' + -fractionSize);

var fraction = ('' + number).split(DECIMAL_SEP);
var whole = fraction[0];
fraction = fraction[1] || '';

var i, pos = 0,
lgroup = pattern.lgSize,
group = pattern.gSize;

if (whole.length >= (lgroup + group)) {
pos = whole.length - lgroup;
for (i = 0; i < pos; i++) {
if ((pos - i) % group === 0 && i !== 0) {
formatedText += groupSep;
}
formatedText += whole.charAt(i);
}
/**
* Format a number into a string
* @param {number} number The number to format
* @param {{
* minFrac, // the minimum number of digits required in the fraction part of the number
* maxFrac, // the maximum number of digits required in the fraction part of the number
* gSize, // number of digits in each group of separated digits
* lgSize, // number of digits in the last group of digits before the decimal separator
* negPre, // the string to go in front of a negative number (e.g. `-` or `(`))
* posPre, // the string to go in front of a positive number
* negSuf, // the string to go after a negative number (e.g. `)`)
* posSuf // the string to go after a positive number
* }} pattern
* @param {string} groupSep The string to separate groups of number (e.g. `,`)
* @param {string} decimalSep The string to act as the decimal separator (e.g. `.`)
* @param {[type]} fractionSize The size of the fractional part of the number
* @return {string} The number formatted as a string
*/
function formatNumber(number, pattern, groupSep, decimalSep, fractionSize) {

if (!(isString(number) || isNumber(number)) || isNaN(number)) return '';

var isInfinity = !isFinite(number);
var isZero = false;
var numStr = Math.abs(number) + '',
formattedText = '',
parsedNumber;

if (isInfinity) {
formattedText = '\u221e';
} else {
parsedNumber = parse(numStr);

roundNumber(parsedNumber, fractionSize, pattern.minFrac, pattern.maxFrac);

var digits = parsedNumber.d;
var integerLen = parsedNumber.i;
var exponent = parsedNumber.e;
var decimals = [];
isZero = digits.reduce(function(isZero, d) { return isZero && !d; }, true);

// pad zeros for small numbers
while (integerLen < 0) {
digits.unshift(0);
integerLen++;
}

for (i = pos; i < whole.length; i++) {
if ((whole.length - i) % lgroup === 0 && i !== 0) {
formatedText += groupSep;
}
formatedText += whole.charAt(i);
// extract decimals digits
if (integerLen > 0) {
decimals = digits.splice(integerLen);
} else {
decimals = digits;
digits = [0];
}

// format the integer digits with grouping separators
var groups = [];
if (digits.length > pattern.lgSize) {
groups.unshift(digits.splice(-pattern.lgSize).join(''));
}
while (digits.length > pattern.gSize) {
groups.unshift(digits.splice(-pattern.gSize).join(''));
}
if (digits.length) {
groups.unshift(digits.join(''));
}
formattedText = groups.join(groupSep);

// format fraction part.
while (fraction.length < fractionSize) {
fraction += '0';
// append the decimal digits
if (decimals.length) {
formattedText += decimalSep + decimals.join('');
}

if (fractionSize && fractionSize !== "0") formatedText += decimalSep + fraction.substr(0, fractionSize);
} else {
if (fractionSize > 0 && number < 1) {
formatedText = number.toFixed(fractionSize);
number = parseFloat(formatedText);
formatedText = formatedText.replace(DECIMAL_SEP, decimalSep);
if (exponent) {
formattedText += 'e+' + exponent;
}
}

if (number === 0) {
isNegative = false;
if (number < 0 && !isZero) {
return pattern.negPre + formattedText + pattern.negSuf;
} else {
return pattern.posPre + formattedText + pattern.posSuf;
}

parts.push(isNegative ? pattern.negPre : pattern.posPre,
formatedText,
isNegative ? pattern.negSuf : pattern.posSuf);
return parts.join('');
}

function padNumber(num, digits, trim) {
Expand All @@ -235,7 +338,7 @@ function padNumber(num, digits, trim) {
num = -num;
}
num = '' + num;
while (num.length < digits) num = '0' + num;
while (num.length < digits) num = ZERO_CHAR + num;
if (trim) {
num = num.substr(num.length - digits);
}
Expand Down
52 changes: 45 additions & 7 deletions test/ng/filter/filtersSpec.js
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Original file line number Diff line number Diff line change
Expand Up @@ -92,6 +92,39 @@ describe('filters', function() {
expect(formatNumber(-0.0001, pattern, ',', '.', 3)).toBe('0.000');
expect(formatNumber(-0.0000001, pattern, ',', '.', 6)).toBe('0.000000');
});

it('should work with numbers that are close to the limit for exponent notation', function() {
// previously, numbers that n * (10 ^ fractionSize) > localLimitMax
// were ending up with a second exponent in them, then coercing to
// NaN when formatNumber rounded them with the safe rounding
// function.

var localLimitMax = 999999999999999900000,
localLimitMin = 10000000000000000000,
exampleNumber = 444444444400000000000;

expect(formatNumber(localLimitMax, pattern, ',', '.', 2))
.toBe('999,999,999,999,999,900,000.00');
expect(formatNumber(localLimitMin, pattern, ',', '.', 2))
.toBe('10,000,000,000,000,000,000.00');
expect(formatNumber(exampleNumber, pattern, ',', '.', 2))
.toBe('444,444,444,400,000,000,000.00');

});

it('should format large number',function() {
var num;
num = formatNumber(12345868059685210000, pattern, ',', '.', 2);
expect(num).toBe('12,345,868,059,685,210,000.00');
num = formatNumber(79832749837498327498274983793234322432, pattern, ',', '.', 2);
expect(num).toBe('7.98e+37');
num = formatNumber(8798327498374983274928, pattern, ',', '.', 2);
expect(num).toBe('8,798,327,498,374,983,000,000.00');
num = formatNumber(879832749374983274928, pattern, ',', '.', 2);
expect(num).toBe('879,832,749,374,983,200,000.00');
num = formatNumber(879832749374983274928, pattern, ',', '.', 32);
expect(num).toBe('879,832,749,374,983,200,000.00000000000000000000000000000000');
});
});

describe('currency', function() {
Expand Down Expand Up @@ -186,13 +219,10 @@ describe('filters', function() {
});

it('should filter exponentially large numbers', function() {
expect(number(1e50)).toEqual('1e+50');
expect(number(-2e100)).toEqual('-2e+100');
});

it('should ignore fraction sizes for large numbers', function() {
expect(number(1e50, 2)).toEqual('1e+50');
expect(number(-2e100, 5)).toEqual('-2e+100');
expect(number(1.23e50)).toEqual('1.23e+50');
expect(number(-2.3456e100)).toEqual('-2.346e+100');
expect(number(1e50, 2)).toEqual('1.00e+50');
expect(number(-2e100, 5)).toEqual('-2.00000e+100');
});

it('should filter exponentially small numbers', function() {
Expand All @@ -206,6 +236,14 @@ describe('filters', function() {
expect(number(-1e-7, 6)).toEqual('0.000000');
expect(number(-1e-8, 9)).toEqual('-0.000000010');
});

it('should filter exponentially small numbers when no fraction specified', function() {
expect(number(1e-10)).toEqual('0.000');
expect(number(0.0000000001)).toEqual('0.000');

expect(number(-1e-10)).toEqual('0.000');
expect(number(-0.0000000001)).toEqual('0.000');
});
});

describe('json', function() {
Expand Down

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