how do I turn a string mathematical operator i.e "+" into a mathematical operator i.e +

Asked Jun 28 '18 at 15:27

Active Jun 28 '18 at 15:30

Viewed 57 times

I have event listeners that push numbers and strings of math operators to an array so it looks like this:

var outputArr = [9 , "+" , 9];

I want to end up with this code:

var readyForMath = 9 + 9;

I've tried using .join("") to make it a string and then passing it into and eval function as so:

var evaluate = eval(outputArr.join(""));

which works but I don't want to use it because its bad practice.

I've tried parse functions such as parseInt() and parseFloat(). However, they return the number only and remove the strings completely. Does anyone know how to achieve this ?

asked Jun 28 '18 at 15:27

Michael Lewell

3

A common way is to create an object with operator methods, like `const operator = {'+': function (a, b) {return a + b;}, ...}`. – Teemu Jun 28 '18 at 15:29
You could stringify your array and the use `eval(str)` to evaluate the answer – Alex Jun 28 '18 at 15:30
1

@Alex I don't think using `eval()` is a good idea... – Ivan Jun 28 '18 at 15:31
@Ivan it is not a good idea, it all depends on what the scale of the project is. – Alex Jun 28 '18 at 15:32
@Alex Stringifying an array preserves the commas, not going to evaluate. – Teemu Jun 28 '18 at 15:32
@Teemu good to be pointed out, Thanks! – Alex Jun 28 '18 at 15:35

how do I turn a string mathematical operator i.e "+" into a mathematical operator i.e +

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