Js简单判断四则运算是否可用

function test(s){ 

    try{

        return !isNaN(eval("("+s+")"));

    }catch(e){

        return false;

    }

}

alert(test("1+6*(2+(3-1)/1+(9-5*1))"));

//--------------------------------------------------------------------------------------

<script>

var str = "1+6*(2+(3-1)/1+(9-5*1))";

try{

    eval("var ret = "+str);

    if(ret!=Infinity){

        alert("right");

    }else{

        alert("wrong");

    }

}catch(e){

    alert("wrong");

}

</script>

//--------------------------------------------------------------------------------------

function test(s){

    var reg=/[\d\.\+\-\*\/\(\)]+/;

    try{

        return ret.test(s)&&!isNaN(eval("("+s+")"));

    }catch(e){

        return false;

    }

}

alert(test("1+6*(2+(3-1)/1+(9-5*1))"));

//--------------------------------------------------------------------------------------

<script>

var s = '1+6*(2+(3-1)/1+(9-5*1))';

if(s.match(/[^\+\-\*\/0-9()]/))

{

    alert('illegal!')

}

else

{

    try

    {

        alert(eval(s));

    }

    catch(e)

    {

        alert('illegal')

    }

}

</script>