I have following array.
var signs = ['+', '-', '*', '/'];
And following variables to add with each sign above in the array.
var right_digit = 1;
var left_digit = 5;
Can I do something like below in JS?
var answer = left_digit sign[0] right_digit;
If you want to avoid eval you can do something like:
var signs = {
'+': function(op1, op2) { return op1 + op2; },
...
};
var answer = signs['+'](left_digit, right_digit);
I'm pretty sure you can't do this, but you can make a function which does that.
function action(a, b, c) {
switch (c) {
case "+":
return a+b;
case "-":
return a-b;
case "*":
return a*b;
default:
return a/b;
}
}
You can use eval if you want dynamically evaluate operators in that way:
var answer = eval(right_digit + sign[0] + left_digit);
Note that the use of `eval is not recommended because of potentional security issues (if the data is untrusted) and slow because the code has to be analysed each time it's executed.
A better way would be using a switch like this:
function calculate(a, operator, b) {
switch (operator) {
case "+":
return a + b;
case "-":
return a - b;
case "*":
return a * b;
case "/":
return a / b;
}
}
var answer = calculate(right_digit, sign[0], left_digit);
eval() was the entirety of your answer ;)You can using eval:
var answer = eval(left_digit + sign[0] + right_digit);
A safe eval solution (will filter digits and sign, and throw an error if it isn't in that format):
function calculate(expr) {
var matches = /^(\d+)([+\-*/])(\d+)$/.exec(expr);
if(!matches) {
throw "Not valid";
}
return eval(matches[1] + matches[2] + matches[3]);
}
calculate('2*4'); // 8
So you can do:
calculate(left + sign + right);
1 + 5.