src/polyfills/math-sign.js - main - githubmirror/amphtml

src/polyfills/math-sign.js

33 строки678 B

Kristofer Baxter

♻️ Remove Notice from JS and Markdown (#35717)

19 авг 2021, 21:21

19 авг 2021, 21:21f564b7e

/**
 * Parses the number x and returns its sign. For positive x returns 1, for
 * negative, -1. For 0 and -0, returns 0 and -0 respectively. For any number
 * that parses to NaN, returns NaN.
 *
 * @param {number} x
 * @return {number}
 */
export function sign(x) {
  x = Number(x);

  // If x is 0, -0, or NaN, return it.
  if (!x) {
    return x;
  }

  return x > 0 ? 1 : -1;
}

/**
 * Sets the Math.sign polyfill if it does not exist.
 * @param {!Window} win
 */
export function install(win) {
  if (!win.Math.sign) {
    win.Object.defineProperty(win.Math, 'sign', {
      enumerable: false,
      configurable: true,
      writable: true,
      value: sign,
    });
  }
}