module.exports = function sprintf() { // discuss at: https://locutus.io/php/sprintf/ // original by: Ash Searle (https://hexmen.com/blog/) // improved by: Michael White (https://getsprink.com) // improved by: Jack // improved by: Kevin van Zonneveld (https://kvz.io) // improved by: Kevin van Zonneveld (https://kvz.io) // improved by: Kevin van Zonneveld (https://kvz.io) // improved by: Dj // improved by: Allidylls // input by: Paulo Freitas // input by: Brett Zamir (https://brett-zamir.me) // improved by: RafaƂ Kukawski (https://kukawski.pl) // example 1: sprintf("%01.2f", 123.1) // returns 1: '123.10' // example 2: sprintf("[%10s]", 'monkey') // returns 2: '[ monkey]' // example 3: sprintf("[%'#10s]", 'monkey') // returns 3: '[####monkey]' // example 4: sprintf("%d", 123456789012345) // returns 4: '123456789012345' // example 5: sprintf('%-03s', 'E') // returns 5: 'E00' // example 6: sprintf('%+010d', 9) // returns 6: '+000000009' // example 7: sprintf('%+0\'@10d', 9) // returns 7: '@@@@@@@@+9' // example 8: sprintf('%.f', 3.14) // returns 8: '3.140000' // example 9: sprintf('%% %2$d', 1, 2) // returns 9: '% 2' const regex = /%%|%(?:(\d+)\$)?((?:[-+#0 ]|'[\s\S])*)(\d+)?(?:\.(\d*))?([\s\S])/g const args = arguments let i = 0 const format = args[i++] const _pad = function (str, len, chr, leftJustify) { if (!chr) { chr = ' ' } const padding = str.length >= len ? '' : new Array((1 + len - str.length) >>> 0).join(chr) return leftJustify ? str + padding : padding + str } const justify = function (value, prefix, leftJustify, minWidth, padChar) { const diff = minWidth - value.length if (diff > 0) { // when padding with zeros // on the left side // keep sign (+ or -) in front if (!leftJustify && padChar === '0') { value = [value.slice(0, prefix.length), _pad('', diff, '0', true), value.slice(prefix.length)].join('') } else { value = _pad(value, minWidth, padChar, leftJustify) } } return value } const _formatBaseX = function (value, base, leftJustify, minWidth, precision, padChar) { // Note: casts negative numbers to positive ones const number = value >>> 0 value = _pad(number.toString(base), precision || 0, '0', false) return justify(value, '', leftJustify, minWidth, padChar) } // _formatString() const _formatString = function (value, leftJustify, minWidth, precision, customPadChar) { if (precision !== null && precision !== undefined) { value = value.slice(0, precision) } return justify(value, '', leftJustify, minWidth, customPadChar) } // doFormat() const doFormat = function (substring, argIndex, modifiers, minWidth, precision, specifier) { let number, prefix, method, textTransform, value if (substring === '%%') { return '%' } // parse modifiers let padChar = ' ' // pad with spaces by default let leftJustify = false let positiveNumberPrefix = '' let j, l for (j = 0, l = modifiers.length; j < l; j++) { switch (modifiers.charAt(j)) { case ' ': case '0': padChar = modifiers.charAt(j) break case '+': positiveNumberPrefix = '+' break case '-': leftJustify = true break case "'": if (j + 1 < l) { padChar = modifiers.charAt(j + 1) j++ } break } } if (!minWidth) { minWidth = 0 } else { minWidth = +minWidth } if (!isFinite(minWidth)) { throw new Error('Width must be finite') } if (!precision) { precision = specifier === 'd' ? 0 : 'fFeE'.indexOf(specifier) > -1 ? 6 : undefined } else { precision = +precision } if (argIndex && +argIndex === 0) { throw new Error('Argument number must be greater than zero') } if (argIndex && +argIndex >= args.length) { throw new Error('Too few arguments') } value = argIndex ? args[+argIndex] : args[i++] switch (specifier) { case '%': return '%' case 's': return _formatString(value + '', leftJustify, minWidth, precision, padChar) case 'c': return _formatString(String.fromCharCode(+value), leftJustify, minWidth, precision, padChar) case 'b': return _formatBaseX(value, 2, leftJustify, minWidth, precision, padChar) case 'o': return _formatBaseX(value, 8, leftJustify, minWidth, precision, padChar) case 'x': return _formatBaseX(value, 16, leftJustify, minWidth, precision, padChar) case 'X': return _formatBaseX(value, 16, leftJustify, minWidth, precision, padChar).toUpperCase() case 'u': return _formatBaseX(value, 10, leftJustify, minWidth, precision, padChar) case 'i': case 'd': number = +value || 0 // Plain Math.round doesn't just truncate number = Math.round(number - (number % 1)) prefix = number < 0 ? '-' : positiveNumberPrefix value = prefix + _pad(String(Math.abs(number)), precision, '0', false) if (leftJustify && padChar === '0') { // can't right-pad 0s on integers padChar = ' ' } return justify(value, prefix, leftJustify, minWidth, padChar) case 'e': case 'E': case 'f': // @todo: Should handle locales (as per setlocale) case 'F': case 'g': case 'G': number = +value prefix = number < 0 ? '-' : positiveNumberPrefix method = ['toExponential', 'toFixed', 'toPrecision']['efg'.indexOf(specifier.toLowerCase())] textTransform = ['toString', 'toUpperCase']['eEfFgG'.indexOf(specifier) % 2] value = prefix + Math.abs(number)[method](precision) return justify(value, prefix, leftJustify, minWidth, padChar)[textTransform]() default: // unknown specifier, consume that char and return empty return '' } } try { return format.replace(regex, doFormat) } catch (err) { return false } }