EVAL() function in Html & JavaScript giving weird results....!

Question

the below code giving some unexpected results. can anyone tell me the reason or logic behind that?

<HTML><body><script type="text/javascript">s="10+10";alert("here 3 : "+eval(s+s+s));alert("here 4 :+eval(s+2));</script></body></HTML>

in first alert it's giving 2040 and in second alert it's giving 112 i'm not able to understand the logic kindly help me.

user2264587 · Accepted Answer · 2013-04-16 06:03:25Z

1

eval is bad practice, howerer to answer your question:

`s="10+10"`

s is now "10+10"

eval(s+s+s) =>

eval("10+10"+"10+10"+"10+10") =>

eval("10+1010+1010+10") =>

2040

and:

eval(s+2) =>

eval("10+10"+2) =>

eval("10+102") =>

112

what you might have meant is:

eval(s+"+"+s+"+"+s)

and

eval(s+"+2")

answered Apr 16, 2013 at 5:57

user2264587

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1 Comment

Eval is not necessarily bad, it's just that in the early days of scripting it was abused.