js variable and radio button checked / unchecked

Question

<input id='rb1' type="radio" name="bafter" checked>
<input id='rb2' type="radio" name="bafter">

js

$(".item").click(function(){
    console.log(a); // 39 (that's ok)
    if ($('#rb1').prop('checked') == true) {a -=1;}
    else {a +=1;}
});

console.log(a);

If rb1 checked result is - 38 (ok)
If rb2 is not checked reusult is - 391 (should be 40)

Any help?

@bonaca - Can you include that in the code? What may be happening is it gets evaluated as a string. And Hence 39+1 is getting converted to 391. string + int in Javascript = string — Vandesh
– Vandesh, Commented Aug 7, 2016 at 14:38

Vandesh · Accepted Answer · 2016-08-07 14:42:58Z

2

a might be getting evaluated as a string.
And string + int = string in Javascript
So, "39" + 1 = "391"
Use a = parseInt(a) + 1; and a = parseInt(a) - 1;

answered Aug 7, 2016 at 14:42

Vandesh

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2 Comments

qadenza Over a year ago

That's it. Have you any link about harmful eval function ?

Vandesh Over a year ago

Why eval is harmful? - stackoverflow.com/questions/86513/…

Ravi Shankar Bharti · Accepted Answer · 2016-08-07 14:30:18Z

2

It is concatenating as a string. Try a =eval("a+1")

answered Aug 7, 2016 at 14:30

Ravi Shankar Bharti

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4 Comments

qadenza Over a year ago

but it should not be concatenated !

Ravi Shankar Bharti Over a year ago

Yes, but JavaScript takes "+" as string concatenator.

qadenza Over a year ago

I will. be patient, pls

Vandesh Over a year ago

eval is harmful and not recommended to be used. Here's why - stackoverflow.com/questions/86513/…

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