js 变量作用域

 

例子

<script>var a = "heh"function findLove(){console.log(a);function findforyou(){var a ="you";console.log(a);}function findother(){console.log(a)}findforyou();findother();}findLove();
</script>

输出

heh
you
heh

 

例子

<script>var test_id = "my love";if(true){console.log(test_id);var test_id = "where my love?";console.log(test_id);}console.log(test_id);
</script>

输出

my love
where my love?
where my love?

 

例子

<script>var test_id = "my love";function findLove(){var test_id ;console.log(test_id);test_id = "is you?";console.log(test_id);}findLove();console.log(test_id);
</script>

输出

undefined
is you?
my love

 

例子

<script>var a = "heh"if(true){console.log(a);}
</script>

输出

heh

 

例子

<script>var a = "heh"function findLove(){console.log(a);}findLove();
</script>

输出

heh

 

例子

<script>var a = "heh"function findLove(){console.log(a);var a}findLove();
</script>

输出

undefined