In the above example, we simply converted the signage when we encountered a minus symbol-- so we need to keep some concept of what sign we're at. This will allow us to keep track of what operation we're performing, whether it's + or -.
Assuming we handle signage with a 1 or a -1, our method so far starts to look something like this:
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function calculator(str) { let result = 0, sign = 1; for (let i = 0; i < str.length; i++) { const curr = str.charAt(i); if (curr === '+') { sign = 1; } else if (curr === '-') { sign = -1; } else if (curr >= '0' && curr <= '9') { let num = curr; while (i + 1 < str.length && str.charAt(i + 1) >= '0' && str.charAt(i + 1) <= '9') { num += str.charAt(i + 1); i++; } result += sign * parseInt(num); } } return result;}OUTPUT
:001 > Cmd/Ctrl-Enter to run, Cmd/Ctrl-/ to comment