lib/bignumber.js
function BigNumber(number) {
    this.numberStr = number.toString();

    // not a number
    if (isNaN(parseFloat(this.numberStr)) === true
        || isFinite(this.numberStr) === false) {
        throw new Error(number + ' is not a number');
    }
}
function BigNumber(number) {
    this.numberStr = number.toString();

    // not a number
    if (isNaN(parseFloat(this.numberStr)) === true
        || isFinite(this.numberStr) === false) {
        throw new Error(number + ' is not a number');
    }
}
function BigNumber ( number ) { this . numberStr = number . toString ( ) ; // not a number if ( isNaN ( parseFloat ( this . numberStr ) ) === true || isFinite ( this . numberStr ) === false ) { throw new Error ( number + ' is not a number' ) ; } }
wraps a large number, does not support arithmetic
wraps a large number does not support arithmetic