Use JS to implement the cube root of any precision number (including negative numbers and decimals) without library functions

Describes computing the cube root of a number without using library functions. Keep one decimal place.

Input description: Parameter to be evaluated, of type double (a real number)

Output description: Cube root of input parameter. Keep one decimal place.

Example 1 Input: 216 Output: 6.0

Example 2 Input: -0.07 Output: -0.4

Example 3 Input: -5 Output: -1.7

const readline = require('readline');


function myProcess(str)
{   
    let tmpNum = BigInt(str);
    let tmpValue =  tmpNum;
    let lastBig;
    let firstLittle;
    tmpValue = (BigInt)(tmpValue / BigInt(2));
    while(true) {
         if(tmpValue**BigInt(3) === tmpNum){
            firstLittle = tmpValue;
            break;
        } else if(tmpValue**BigInt(3) > tmpNum){
            lastBig = tmpValue;
            tmpValue = (BigInt)(tmpValue / BigInt(2));
        } else{
            firstLittle = tmpValue;
            break; }}let i=firstLittle;
    for(i=firstLittle; i<lastBig; i++){if(BigInt(i)**BigInt(3) > tmpNum)
            break;
    }
    let start = Number(i) - 1;
    let step = 0.1;
    let result;
    for(letj=start; j<start+1;) {if((BigInt(j*10) * *BigInt(3) / BigInt(1000)) > tmpNum){
            result = j;
            break;
        }
        j += 0.1; 
        j = Number(Number(j).toFixed(1));
    }

    if ((BigInt(result*10) * *BigInt(3) - tmpNum*BigInt(1000)) < (tmpNum*BigInt(1000) - BigInt(Number(Number(result-0.1).toFixed(1)) *10) * *BigInt(3))){
        result = Number(result).toString();
    } else {
        result = Number(Number(result-0.1).toFixed(1)).toString();
    }
    if(result.length == 1){
        result+='0';
    }
    return result;
}


const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
});

rl.on('line'.function (line) {
    let minus = false;
    let factor = 0;
    if(line[0] = =The '-'){
        minus = true;
        line = line.substring(1); }let dotIndex = line.indexOf('. ');
    if(dotIndex>-1){
        line = (Number(line)*1000).toString();
        factor = 1;// The cube root needs to be reduced by 10 times
        //factor = line.substring(dotIndex+1).length;
    }

    try{
        //line = line.replace('.','')
        let tmpResult = myProcess(line);
        if(minus) {// Negative numbers need to be corrected
            tmpResult = Number(Number(Number(tmpResult)-0.1).toFixed(1)); 
        }
        tmpResult = Number(tmpResult)/(10**factor);
        tmpResult = tmpResult.toFixed(1);
        if(minus) {
            tmpResult = The '-'+tmpResult;
        }
        console.log(tmpResult);
    }catch(e){
        console.log(line); }});Copy the code