在javascript中的变量名之前使用var是否有任何区别/优势？

Question

I am learning javascript . And I noted that the instructor was making variables in two ways . first was (for example):

var name ="Any string here";

and second method was simply writing the variable name without writing var first :

name="Any string here";

And the result was same . So , is there any difference between these two ?. Which one is better to use ?

Answer 1

离开了var使其成为一个全局变量，所以如果你有name多个地方的代码，他们会互相覆盖。

Answer 2

• First of all, it is a bad practice to not write var before variable declaration.
• Second problem is a global declaration of variable without var .
• Third, in strict mode using variable without declaration will cause Exception