Example analysis of function declaration taking precedence over variable declaration in JavaScript_javascript skills

Copy code The code is as follows:

var a; // Declare a variable with identifier a
function a() { // Declare a function, the identifier is also a
}
alert(typeof a);

displays "function", which is the priority of function Level higher than var.
Some people think this is the reason why the code is executed sequentially, that is, a is overwritten by the funcion executed later. Okay, swap them around.

Copy code The code is as follows:

function a() {
}
var a;
alert(typeof a);

The result still shows "function" instead of "undefined". That is, function declarations take precedence over variable declarations.
We slightly modify the code and assign a value when declaring a.

Copy code The code is as follows:

function a() {
}
var a = 1; // Note here
alert(typeof a);

At this time, "number" is displayed but not "function", which is equivalent to

Copy code The code is as follows:

function a() {
}
var a;
a = 1; // Note here
alert(typeof a);

means "var a = 1" is split into two steps. a has been reassigned, naturally it is the last value.