Package Exports

string-math

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Readme

Description

string-math is a module (function) that computes the [Number] result from the [String] arithmetical formula.

It does not use eval()
It uses regular expressions to parse [String] equations

"2 + 2"  //4
"3*(5-2)"  //9
" 2.5  *   2.5  /   .1" //62.5
"3.5+5*(-4-(3/(3+1)-12*3-.2*22)-16/4*12-5/(2)+3.5+2.5*(1.5-2*7))-16" //-225.5

Any bugs found? Give me to know on GitHub
Also check out exact-math to compute arithmetical formulas with precise floating point values; (get rid of 0.30000000000000004 values)

Installation

with NodeJS / bundlers

npm install string-math

var stringMath = require('string-math');

stringMath("--1") //1
stringMath("2/-2") //-1
stringMath("-5-5") //-10

with Browser

1. Add string-math.js to the HTML file.

<head>
  <script src="./string-math.js"></script>
</head>

Any other dependencies are needed.

2. Use `stringMath` global Function from `string-math.js`.

var result = stringMath("2+2");

Browser Support

Chrome	Firefox	IE	Safari	Opera
yes	yes	yes	yes	yes

Tests

> git clone https://github.com/devrafalko/string-math.git
> cd string-math
> npm install
> npm test
> npm test deep //displays error messages

Usage

`stringMath(expression)`

`expression` [String]

the arithmetical formula
it can contain:
- [0-9] digits
- 1.5, 0.5 or .5 decimal fractions
- -5, -.4, -5.55 negative values
- * multiplication sign
- / division sign
- + plus sign
- - subtraction sign
- ( and ) parentheses

Tips

the arithmetic order of operations is respected:
- parentheses first
- then division and multiplication (from left to right)
- then addition and subtraction (from left to right)
the multiplication sign can be omitted before parentheses; 4(2+1); equals to 4*(2+1)
the following signs combinations are allowed:
- 2 * -2; equals to 2 * (-2)
- 2 / -2; equals to 2 / (-2)
- +2 + 2; equals to 2 + 2
- 2 + +2; equals to 2 + 2
- -2 - -2 equals to -2 + 2
- -2 - +2 equals to -2 - 2
- -2 + -2 equals to -2 - 2
the (multi)spaces between values, signs and parentheses are allowed:
- 2 + 2
- 2 + ( -2 - -2)
- 2 + (+2 + +4 / -1)
- -.1 - -5
the spaces are not allowed between:
- negative sign and value: -2 - - 2
- period and digit in decimal fraction: 5 + . 3
- uneven opening and closing brackets: 5 + (3 * (3 + 4)

string-math