The Math.floor()
function returns the largest integer less than or equal to a given number.
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Syntax
Math.floor(x)
Parameters
x
- A number.
Return value
A number representing the largest integer less than or equal to the specified number.
Description
Because floor()
is a static method of Math
, you always use it as Math.floor()
, rather than as a method of a Math
object you created (Math
is not a constructor).
Note: Math.floor(null)
returns 0, not a NaN
.
Examples
Using Math.floor()
Math.floor( 45.95); // 45 Math.floor( 45.05); // 45 Math.floor( 4 ); // 4 Math.floor(-45.05); // -46 Math.floor(-45.95); // -46
Decimal adjustment
/** * Decimal adjustment of a number. * * @param {String} type The type of adjustment. * @param {Number} value The number. * @param {Integer} exp The exponent (the 10 logarithm of the adjustment base). * @returns {Number} The adjusted value. */ function decimalAdjust(type, value, exp) { // If the exp is undefined or zero... if (typeof exp === 'undefined' || +exp === 0) { return Math[type](value); } value = +value; exp = +exp; // If the value is not a number or the exp is not an integer... if (isNaN(value) || !(typeof exp === 'number' && exp % 1 === 0)) { return NaN; } // Shift value = value.toString().split('e'); value = Math[type](+(value[0] + 'e' + (value[1] ? (+value[1] - exp) : -exp))); // Shift back value = value.toString().split('e'); return +(value[0] + 'e' + (value[1] ? (+value[1] + exp) : exp)); } // Decimal round const round10 = (value, exp) => decimalAdjust('round', value, exp); // Decimal floor const floor10 = (value, exp) => decimalAdjust('floor', value, exp); // Decimal ceil const ceil10 = (value, exp) => decimalAdjust('ceil', value, exp); // Round round10(55.55, -1); // 55.6 round10(55.549, -1); // 55.5 round10(55, 1); // 60 round10(54.9, 1); // 50 round10(-55.55, -1); // -55.5 round10(-55.551, -1); // -55.6 round10(-55, 1); // -50 round10(-55.1, 1); // -60 // Floor floor10(55.59, -1); // 55.5 floor10(59, 1); // 50 floor10(-55.51, -1); // -55.6 floor10(-51, 1); // -60 // Ceil ceil10(55.51, -1); // 55.6 ceil10(51, 1); // 60 ceil10(-55.59, -1); // -55.5 ceil10(-59, 1); // -50
Specifications
Specification |
---|
ECMAScript (ECMA-262) The definition of 'Math.floor' in that specification. |
Browser compatibility
The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Desktop | Mobile | Server | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
floor | Chrome Full support 1 | Edge Full support 12 | Firefox Full support 1 | IE Full support 3 | Opera Full support 3 | Safari Full support 1 | WebView Android Full support 1 | Chrome Android Full support 18 | Firefox Android Full support 4 | Opera Android Full support 10.1 | Safari iOS Full support 1 | Samsung Internet Android Full support 1.0 | nodejs Full support 0.1.100 |
Legend
- Full support
- Full support