How to Pass an Operator e.g., * / + -
4 Message(s) by 3 Author(s) originally posted in javascript programming
| From: vbgunz |
Date: Saturday, October 27, 2007
|
function operator (a, b) {
return a + b;
}
without the use of eval, how'd you change the + operator into say
* ? If you cannot pass operators in any form what'd be the best
thing to do here or'd the best thing to do in this case is use
eval?
| From: Bart Van der Donck |
Date: Saturday, October 27, 2007
|
wrote in message:
function operator(a, b) {
return a + b;
}
without the use of eval, how'd you change the + operator into say
* ? If you cannot pass operators in any form what'd be the best
thing to do here or'd the best thing to do in this case is use
eval?
I do not believe this is possible then.
The
list of operators is limited (*), so I'd do something like
this:
function operator(a, b, op) {
if (op == 'plus') return a + b;
if (op == 'mult') return a * b;
if (op == 'minus') return a - b;
}
(*)
http://www.w3schools.com/js/js_operators.asp
Hope this helps,
--
Bart
| From: vbgunz |
Date: Saturday, October 27, 2007
|
wrote in message:
wrote in message:
> function operator(a, b) {
> return a + b;
> }
>
> without the use of eval, how'd you change the + operator into say
> * ? If you cannot pass operators in any form what'd be the best
> thing to do here or'd the best thing to do in this case is use
> eval?
I do not believe this is possible then.
The list of operators is limited (*), so I'd do something like
this:
function operator(a, b, op) {
if (op == 'plus') return a + b;
if (op == 'mult') return a * b;
if (op == 'minus') return a - b;
}
(*)
http://www.w3schools.com/js/js_operators.asp
Hope this helps,
--
Bartit all started with the following function. I am bad at math and
date s
and while looking over some date methods I came up with this...
// Basic Date Arithmetic
var dateObject = new Date(2007, 9, 27);
// 01: this
version can only do addition :/
function bda0(d, h, i) {
var d = new Date(d);
return new Date(d['set' + h](d['get' + h]() + i));
}
print(bda0(dateObject, 'Date', 5));
I was stumped and ended up doing something like what you mentioned
using the
switch statement and a anonymous function. I did not like it :
(
ultimately, this is what I have now but it uses eval. I really dislike
the idea of using eval but this was the shortest, most readable and
most concise version. please
break it.
// 02: this version can add, multiply, divide and subtract
function bda(d, h, i) {
var d = new Date(d);
var o = /(^[+*/-])?(\w+)/g.exec(h)[1]; // operator
var h = /(^[+*/-])?(\w+)/g.exec(h)[2]; // handler
return eval("new Date(d['set' + h](d['get' + h]()" + o + "i));");
}
print(bda(dateObject, '+Date', 5));
I went looking through Number and Math and thought I might have missed
such operators but guess this may have to do. any suggestions?
| From: Thomas PointedEars Lahn |
Date: Saturday, October 27, 2007
|
wrote in message:
function operator(a, b) { return a + b; }
[...] how'd you change the + operator into say * ? [...]'d the
best thing to do in this case is use eval?
eval() is designed exactly for those cases; see ES3 Final, 15.1.2.1.PointedEars
--
realism:
HTML 4.01 Strict
evangelism:
XHTML 1.0 Strict
madness: XHTML 1.1 as application/xhtml+xml
-- Bjoern Hoehrmann
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