A Javascript function to run a Newton's Method sequence

newton.js

const newton = (x0, fn, derivative, precision=3, array=false) => {

    const estimates = [x0]

    let next, last, variation = 1
    while ( variation > (Math.pow(10, (-1 * precision))) ){
        last = estimates.slice(-1)[0]

        next = last - (fn(last)/derivative(last))
        estimates.push(next)
        
        variation = Math.abs(next-last)
    }
    
    if (array) { return estimates }
    else { return estimates.slice(-1)[0] }

}

const f = (x) => {
    return (Math.pow(x,3))-5
}

const df = (x) => {
    return 3*(Math.pow(x,2))
}

console.log(newton(1.5, f, df, 3))