CODEWITHSUNDEEP
javascript
inimene
inimene

Reputation: 1650

Wanting to convert a string

So I have this code in which I am attempting to create a simple calculator:

window.onload = function () {make_buttons ('calc'); }

function make_buttons (id) {
    var parent = document.getElementById(id);
        var input = document.createElement("input");
        input.type = 'text'; input.id = 'inp';
        parent.appendChild(input);
        for (var i = 0;i < 10; i++){
            var btn = document.createElement ("button");
            btn.innerHTML = i;
            btn.id = i;
            parent.appendChild(btn);
            (function(index) {btn.onclick = function() {input.value += index;}})(i);
        }

        var multiply = document.createElement ("button");
        multiply.innerHTML = "*";
        multiply.id = "*";
        parent.appendChild(multiply);
        multiply.onclick = function () {input.value += '*';};
        var divide = document.createElement ("button");
        divide.innerHTML = "/";
        divide.id = "/";
        parent.appendChild(divide);
        divide.onclick = function () {input.value += '/';};
        var add = document.createElement ("button");
        add.innerHTML = "+";
        add.id = "+";
        parent.appendChild(add);
        add.onclick = function () {input.value += '+';};
        var substract = document.createElement ("button");
        substract.innerHTML = "-";
        substract.id = "-";
        parent.appendChild(substract);
        substract.onclick = function () {input.value += '-';};
        var calc_it = document.createElement ("button");
        calc_it.innerHTML = "=";
        calc_it.id = "=";
        parent.appendChild(calc_it);
        calc_it.onclick = function () {calculate ()};

};

function calculate () {
    var info = document.getElementById ('inp').value;
    console.log(info);


};

So right now when I click the buttons and make the input field have 5 * 5 inside of it for instance - the var info will equal a string "5 * 5". How could I convert this string so that the numbers in the string will be integers and the operators like * or - will also be non string?

Do I need to include some regex code here?

Upvotes: 1

Views: 81

Answers (1)

Jesse
Jesse

Reputation: 2830

The answer to this question is a difficult one indeed. The obvious and most unpopular answer is an eval, but most likely you are not going to want that.

Basically you will have to code a routine to extract anything you want to use in the expression.

Without using eval or a 3rd party library like 'silentmatts' solution ( below ) you may have to develop your own routine to parse the data.

3rd Party Solution:

Site: http://silentmatt.com/javascript-expression-evaluator/

Git: https://github.com/silentmatt/js-expression-eval

With all of that said, as far as turning a string into a mathematical equation, i personally use eval.

Hope this helps.

Upvotes: 1

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