eval is not calculate if zero before the number

Question

var values = ["50.00024+40.04005+0.1", "0050.00024+040.04005+0.1"];

for (var i=0; i<values.length; i++) {
  if(values[i].indexOf('+')>0 || values[i].indexOf('-')>0 || values[i].indexOf('*')>0 || values[i].indexOf('/')>0){
    try{
      var evaluated = eval(values[i]);
      if(typeof evaluated === 'number'){
        console.log(evaluated);
      }
    }catch (e){
      console.error(e)
    }
  }
}

I have some math actions, it's could be plus, minus or other actions, and I need to take result for this actions. I use eval for this. But if I have zero before number like 005,75 eval is not working. How can I calculate this?

Don't use eval... Split the strings on the allowed operations, convert the numbers to actual numbers and then compute the result. — Andreas, Oct 27 '17 at 15:00
I was thinking about it, but eval is short way.. perhaps you are right. short way is not allways better — YoroDiallo, Oct 27 '17 at 15:03
A zero in front of a number in Javascript is Octal notation. eg. `var a = 010` = 8 — Keith, Oct 27 '17 at 15:04
@GeorgeCampbell That's because parseInt has a default radix of 10.. And he's not using parseInt. — Keith, Oct 27 '17 at 15:07
I suggest using https://stackoverflow.com/a/14990194/5674976 — George, Oct 27 '17 at 15:12

score 2 · Accepted Answer · edited Oct 27 '17 at 15:34

2

You can split the strings and parse the numbers, and then make them into a string again to use eval

var values = ["50.00024+40.04005+0.1", "0050.00024+040.04005+0.1"];
values.forEach(function(value){
    var newValue = value.split(/([\+\-\*\/])/).map(a => parseFloat(a) || a).join('');
    var evaluated = eval(newValue);
    console.log(value,"==", evaluated);
});

edited Oct 27 '17 at 15:34

George

2,330
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answered Oct 27 '17 at 15:11

shawon191

1,945
13
28

score 2 · Answer 2 · answered Oct 27 '17 at 15:32

2

There are various libraries like math.js that can be used to evaluate expressions:

console.log(math.eval("0050.00024+040.04005+0.1"))

<script src="https://cdnjs.cloudflare.com/ajax/libs/mathjs/3.16.5/math.min.js"></script>

answered Oct 27 '17 at 15:32

Slai

22,144
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this is probably the more secure answer – George Oct 27 '17 at 15:41

Gabri T · Answer 3 · 2017-10-27T15:07:09.343

0

you should convert it to float (ex. parseFloat("005.75") = 5.75 instead of evaluating strings

edited Oct 27 '17 at 15:07

answered Oct 27 '17 at 14:58

Gabri T

454
2
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score -1 · Answer 4 · answered Oct 27 '17 at 15:11

-1

Given code at Question you can use .match() to get number values, .map() and .reduce() to add the values

var values = ["50.00024+40.04005+0.1", "0050.00024+040.04005+0.1"];

var res = values.map(function(n) {
  return n.match(/[\d.]+/g).reduce(function(a, b) {
    return a + Number(b)
  }, 0)
});

console.log(res);

answered Oct 27 '17 at 15:11

guest271314

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Looking at this line `values[i].indexOf('+')>0 || values[i].indexOf('-')>0 || values[i].indexOf('*')>0 || values[i].indexOf('/')>0` the questioner is expecting other operators too. – shawon191 Oct 27 '17 at 15:14
@shawon191 The same approach can be used where the operator is matched using `RegExp` `/[-+*][\d.]+/g`, see also [Chrome App: Doing maths from a string](https://stackoverflow.com/questions/32982719/chrome-app-doing-maths-from-a-string) – guest271314 Oct 27 '17 at 15:19
I think the linked answer won't help for `*` or `/`. – shawon191 Oct 27 '17 at 15:23
1

My answer does not omit the operators. `/([\+\-\*\/])/` notice the wrapping first brackets in the regex, which are used to prevent omitting the splitting symbol. – shawon191 Oct 27 '17 at 15:30

eval is not calculate if zero before the number

4 Answers4