| var root = require('./_root'), |
| toInteger = require('./toInteger'), |
| toNumber = require('./toNumber'), |
| toString = require('./toString'); |
| |
| /* Built-in method references for those with the same name as other `lodash` methods. */ |
| var nativeIsFinite = root.isFinite, |
| nativeMin = Math.min; |
| |
| /** |
| * Creates a function like `_.round`. |
| * |
| * @private |
| * @param {string} methodName The name of the `Math` method to use when rounding. |
| * @returns {Function} Returns the new round function. |
| */ |
| function createRound(methodName) { |
| var func = Math[methodName]; |
| return function(number, precision) { |
| number = toNumber(number); |
| precision = precision == null ? 0 : nativeMin(toInteger(precision), 292); |
| if (precision && nativeIsFinite(number)) { |
| // Shift with exponential notation to avoid floating-point issues. |
| // See [MDN](https://mdn.io/round#Examples) for more details. |
| var pair = (toString(number) + 'e').split('e'), |
| value = func(pair[0] + 'e' + (+pair[1] + precision)); |
| |
| pair = (toString(value) + 'e').split('e'); |
| return +(pair[0] + 'e' + (+pair[1] - precision)); |
| } |
| return func(number); |
| }; |
| } |
| |
| module.exports = createRound; |