我想把一个JavaScript的bigint
值转换成科学计数法的字符串
。
我考虑使用Number.toExponential()
,但它只适用于数字
。
const scientificNotation = n => parseInt(n).toExponential();
console.log(scientificNotation(prompt()));
我想把一个JavaScript的bigint
值转换成科学计数法的字符串
。
我考虑使用Number.toExponential()
,但它只适用于数字
。
const scientificNotation = n => parseInt(n).toExponential();
console.log(scientificNotation(prompt()));
事实证明,BigInt.prototype.toLocaleString()
可以使用 options
进行科学计数法格式化:
const fmt /*: BigIntToLocaleStringOptions */ = {
notation: 'scientific',
maximumFractionDigits: 20 // The default is 3, but 20 is the maximum supported by JS according to MDN.
};
const b1 = 1234567890123456789n;
console.log( b1.toLocaleString( 'en-US', fmt ) ); // "1.234567890123456789E18"
(如果您需要超过20位数字的精度或JS环境不支持Intl
,则此代码仍然有用):
由于bigint
值始终是整数,并且bigint.toString()
将返回基于10进制的数字而无需其他仪式(除了负值的前导-
),因此一种快速而简单的方法是获取这些渲染数字并在第一个数字后插入基数点(也称为小数点),并在末尾添加指数,因为它是一个基于10进制的字符串,所以指数与渲染字符串的长度相同(很整洁,对吧?)
function bigIntToExponential( value: bigint ): string {
if( typeof value !== 'bigint' ) throw new Error( "Argument must be a bigint, but a " + ( typeof value ) + " was supplied." );
//
const isNegative = value < 0;
if( isNegative ) value = -value; // Using the absolute value for the digits.
const str = value.toString();
const exp = str.length - 1;
if( exp == 0 ) return ( isNegative ? "-" : '' ) + str + "e+0";
const mantissaDigits = str.replace( /(0+)$/, '' ); // Remove any mathematically insignificant zeroes.
// Use the single first digit for the integral part of the mantissa, and all following digits for the fractional part (if any).
let mantissa = mantissaDigits.charAt( 0 );
if( mantissaDigits.length > 1 ) {
mantissa += '.' + mantissaDigits.substring( 1 );
}
return ( isNegative ? "-" : '' ) + mantissa + "e+" + exp.toString();
}
console.log( bigIntToExponential( 1n ) ); // "1e+0"
console.log( bigIntToExponential( 10n ) ); // "1e+1"
console.log( bigIntToExponential( 100n ) ); // "1e+2"
console.log( bigIntToExponential( 1000n ) ); // "1e+3"
console.log( bigIntToExponential( 10000n ) ); // "1e+4"
console.log( bigIntToExponential( 1003n ) ); // "1.003e+3"
console.log( bigIntToExponential( 10000000003000000n) ); // "1.0000000003e+16"
console.log( bigIntToExponential( 1234567890123456789n ) ); // "1.234567890123456789e+18"
console.log( bigIntToExponential( 12345678901234567898765432109876543210n ) ); // "1.234567890123456789876543210987654321e+37"
console.log( bigIntToExponential( -1n ) ); // "-1e+0"
console.log( bigIntToExponential( -10n ) ); // "-1e+1"
console.log( bigIntToExponential( -100n ) ); // "-1e+2"
console.log( bigIntToExponential( -1000n ) ); // "-1e+3"