JavaScript some common questions to interview summary

1. Questions about function call variables

var a =10;    function aaa(){        alert(a);    }    function bbb(){        var20;        //10    }    bbb();

1. Variable declaration issues

function aaa(){        var a=b=10;    }    aaa();    alert(a);//not defined    alert(b);//10

1. Variable lookup is the nearest principle to find, Var defined variables, when the nearest is not found, will look for the outer layer:

var10    function aaa(){        alert(a);        var a =20;    }    aaa();//undefined

4. When the parameter is the same as the local variable, the priority is the equivalent

  var10;  function aaa(a){      alert(a);      var20;  }  //10

JavaScript some common questions to interview summary