var a = number; // тут у нас число var b = secondnumber; // тут у нас второе число var action = '+'; //действие допустим добавление var result = a + action + b; // сделаем пример 1 + 1 console.log(result); //результат выведет нам 1+1, а вместо этого нам нужно 2! How can you implement exactly the mathematical action and not just add the text together? The topic seems to be simple, but I cannot understand what the matter is, I will be grateful for your help!
Something like that
var operation = { '+' : function( a, b ) { return a + b; } }; var a = number; // тут у нас число var b = secondnumber; // тут у нас второе число var action = '+'; //действие допустим добавление var result = operation[action]( a, b ); // сделаем пример 1 + 1 console.log(result); //результат выведет 2 Here is an example of the page with the proposed solution.
<!DOCTYPE html> <html> <head> <meta charset="utf-8" /> <title></title> </head> <body> <h1>Test of operation plus</h1> <script> window.onload = function (firstNumber, secondNumber) { var operation = { "+": function (a, b) { return a + b; } }; var a = firstNumber; var b = secondNumber; var action = "+"; var result = operation[action](a, b); alert(result); }(1, 2); </script> </body> </html> In the alert displays the number 3 .
Source: https://ru.stackoverflow.com/questions/590630/
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evalthat allows to execute arbitrary code. Without its use, just like in any other language: using the parsing of the expression, or as in the answer below, check the sign immediately and perform the corresponding function - Grundy