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calculate string value in javascript

Lively Ladybird answered on December 24, 2020 Popularity 7/10 Helpfulness 5/10

answer calculate string value in javascript

related calculate string value in javascript

calculate string value in javascript

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function calculate(input) {

  var f = {
    add: '+',
    sub: '-',
    div: '/',
    mlt: '*',
    mod: '%',
    exp: '^'
  };

  // Create array for Order of Operation and precedence
  f.ooo = [
    [
      [f.mlt],
      [f.div],
      [f.mod],
      [f.exp]
    ],
    [
      [f.add],
      [f.sub]
    ]
  ];

  input = input.replace(/[^0-9%^*\/()\-+.]/g, ''); // clean up unnecessary characters

  var output;
  for (var i = 0, n = f.ooo.length; i < n; i++) {

    // Regular Expression to look for operators between floating numbers or integers
    var re = new RegExp('(\\d+\\.?\\d*)([\\' + f.ooo[i].join('\\') + '])(\\d+\\.?\\d*)');
    re.lastIndex = 0; // take precautions and reset re starting pos

    // Loop while there is still calculation for level of precedence
    while (re.test(input)) {
      output = _calculate(RegExp.$1, RegExp.$2, RegExp.$3);
      if (isNaN(output) || !isFinite(output)) 
        return output; // exit early if not a number
      input = input.replace(re, output);
    }
  }

  return output;

  function _calculate(a, op, b) {
    a = a * 1;
    b = b * 1;
    switch (op) {
      case f.add:
        return a + b;
        break;
      case f.sub:
        return a - b;
        break;
      case f.div:
        return a / b;
        break;
      case f.mlt:
        return a * b;
        break;
      case f.mod:
        return a % b;
        break;
      case f.exp:
        return Math.pow(a, b);
        break;
      default:
        null;
    }
  }
}

Popularity 7/10 Helpfulness 5/10 Language javascript

Source: stackoverflow.com

Tags: javascript string

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Contributed on Mar 02 2021

Lively Ladybird

0 Answers Avg Quality 2/10

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calculate string value in javascript

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<div>
  <label for="input">Equation: </label>
  <input type="text" id="input" value="12/5*9+9.4*2-1" />
  <input type="button" 
         value="calculate" 
         onclick="getElementById('result').value = calculate(getElementById('input').value)" />
</div>

<div>
  <label for="result">Result: </label>
  <input type="text" id="result" />
</div>

Popularity 8/10 Helpfulness 2/10 Language javascript

Source: stackoverflow.com

Tags: javascript string javascrip

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Contributed on Mar 02 2021

Lively Ladybird

0 Answers Avg Quality 2/10

calculate string value in javascript

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let res2 = (new Function('return '+str)())

Popularity 7/10 Helpfulness 1/10 Language javascript

Source: Grepper

Tags: javascript string javascrip

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Contributed on Dec 24 2020

Dead Donkey

0 Answers Avg Quality 2/10

calculate string value in javascript

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label {
  display: inline-block;
  width: 4em;
}

Popularity 6/10 Helpfulness 1/10 Language javascript

Source: stackoverflow.com

Tags: javascript string

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Contributed on Mar 02 2021

Lively Ladybird

0 Answers Avg Quality 2/10

calculate string value in javascript

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calculate string value in javascript

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