How to store operator in variable using javascript

Question

I want to store "+" operator in variable.

<head>
<script type="text/javascript">
var m= function(a,b){
return a-b
}
var jj= 10 m 10;
alert(jj)
</script>
</head>

Javascript doesn't support operator overloading, however @dystroy's answer is interesting, but nothing more than the same as doing an add() function. — Lloyd, Feb 01 '13 at 19:34
You didn't put the output that you're expecting from alert(jj), don't leave us guessing... — Louis Ricci, Feb 01 '13 at 19:36

score 25 · Accepted Answer · answered Feb 01 '13 at 19:33

25

Avoiding the use of eval, I would recommend to use a map of functions :

var operators = {
   '+': function(a, b){ return a+b},
   '-': function(a, b){ return a-b}
}

Then you can use

var key = '+';
var c = operators[key](3, 5);

Note that you could also store operators[key] in a variable.

answered Feb 01 '13 at 19:33

Denys Séguret

372,613
87
782
758

You're a legend :) thumbs up :+1 – A l w a y s S u n n y Oct 08 '18 at 16:13

score 0 · Answer 2 · answered Feb 01 '13 at 19:36

0

You cannot store an operator in JavaScript like you have requested. You can store a function to a variable and use that instead.

var plus = function(a, b) { 
    return a + b;
}

Sorry, but JavaScript does not allow this operator overloading.

answered Feb 01 '13 at 19:36

Ryan

21
3

score 0 · Answer 3 · answered Feb 01 '13 at 19:39

You cannot.

There are ways to use javascript to implement custom versions of operators by playing into the available hooks, but there is no possible way to turn m functionally into +.

@dystroy has an excellent example of using the available hooks to implement a custom version of operators, but note that it is still just a classic example of using an object to access functions which do some work.

How to store operator in variable using javascript

3 Answers3

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