1015 B
const infix = expr => {
let rpn = ''
let solve = expr.replace(/^/g,'').match(/([0-9]+|[+()/-]|*+)/g).filter(el => !/\s+/.test(el) && el !== '')
let stack = []
let precedence = {'':5,'/':4,'*':4,'+':3,'-':3}
solve.forEach(symbol => {
if(!isNaN(parseFloat(symbol)) && isFinite(symbol)){
rpn += symbol + ' '
}
else if (Object.keys(precedence).includes(symbol)) {
while(((precedence[symbol] < precedence[stack[stack.length-1]]) || ((precedence[symbol] == precedence[stack[stack.length-1]]) && symbol !== "**"))&&(stack[stack.length - 1] !== '(')) {
rpn += stack.pop() + ' '
}
stack.push(symbol)
}
else if(symbol === '('){stack.push(symbol)}
else if(symbol === ')'){while (stack[stack.length - 1] !== '('){rpn += stack.pop() + ' '; if (stack.length === 0){throw Mismatched parantheses}} stack.pop()}
else {throw ${symbol} is not a recognized symbol}
})
while(stack.length !== 0){
rpn += stack.pop() + ' '
}
return rpn
}