Possible Duplicate:
Running an equation with Javascript from a text field
How can I convert the following:
var n = "2x^3+3x+6";
To
var x = a number
var n = 2x^3+3x+6;
In JavaScript?
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Max Hudson
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2You'll have to write a parser for the expression grammar you intend to use. – Pointy Jan 10 '13 at 16:50
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The `^` operator in JavaScript is binary XOR, not the power as you seem to expect. – Bergi Jan 10 '13 at 16:50
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What operators are you expecting in the equation? – ATOzTOA Jan 10 '13 at 16:53
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http://zaach.github.com/jison/ – bfavaretto Jan 10 '13 at 17:03
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4I don't think this is a duplicate at all; the syntax in this question is definitely not JavaScript. – Pointy Jan 10 '13 at 17:08
2 Answers
17
var x = a number;
var n = eval("2*Math.pow(x,3)+3*x+6")
Shmiddty
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Michaël Benjamin Saerens
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5@PeteH the question isn't necessarily poorly-asked; perhaps the OP does not want to use JavaScript syntax for his equations. – Pointy Jan 10 '13 at 17:09
17
Quite hard to guess what the exact requirements and the context are, but if you want to roughly stick to the grammar demonstrated by your variable I'd suggest using a math expression parser.
Using js-Expression-eval, it could look like this:
var formula = "2*x^3+3*x+6";
var expression = Parser.parse(formula);
var result = expression.evaluate({ x: 3 });
Run the Fiddle
Should you want to have your own grammar - to leave out the * symbols for multiplication with variables, for example - you'll have to roll your own parser, for example using something like jison.
tjdecke
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