Linear Equation Solver | Sololearn

linearSolver.js

function linearSolver(equation) {
  const equa = equation.split('=').map((x) => x.replace(/\s/g, ''))
  const hasX = equa.find((x) => /x/.test(x))
  const noX = equa.find((x) => !/x/.test(x))
  let x = 0
  const errorMsg = 'Invalid Equation: ' + equation
  try {
    if (/\b\W/.test(hasX)) {
      const c = hasX.match(/(-|\+|)+(\d+x|x\d+)/)[0]
      const b = Number(noX)
      const a = Number(hasX.replace(c, ''))
      let operator = '-'
      // change the a coefficient operator to - or +
      ;/^(\+|)/.test(a) ? (operator = ' - ') : (operator = ' + ')
      x =
        Function('return ' + b + operator + a)() /
        Number(c.replace(/(-|\+|)x/, ''))
    } else {
      x = Function('return ' + noX)() / Number(hasX.replace(/x/, ''))
    }
  } catch (e) {
    throw new Error(errorMsg)
  }
  return isNaN(x) ? errorMsg : equation + '\n\n' + ' x = ' + x
}
console.log(linearSolver('2x = 1 - 3')) // -1
console.log(linearSolver('47 = -5x - 10')) // -11.4
console.log(linearSolver('x9 = 5 - 10')) // -0.5555555555555556
console.log(linearSolver('12 + 10 = -x47'))  // -0.46808510638297873
console.log(linearSolver('-5x + -100 = 67')) // Invalid Equation: -5x + -100 = 67
console.log(linearSolver('10x + 140 = 57')) //  x = -8.3
console.log(linearSolver('1x - 10 = 5x7')) //  Invalid Equation: 1x - 10 = 5x7
console.log(linearSolver('100 - -xxx90 = 17')) // Invalid Equation: 100 - -xxx90 = 17