funcunit/site/node_modules/core-js/library/modules/$.is-integer.js

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// 20.1.2.3 Number.isInteger(number)
var isObject = require('./$.is-object')
  , floor    = Math.floor;
module.exports = function isInteger(it){
  return !isObject(it) && isFinite(it) && floor(it) === it;
};