JavaScript 中对变量和函数声明的“提前（hoist）”

var FUNCTION_NAME = function() { /* FUNCTION_BODY */};

function FUNCTION_NAME () 
{ /* FUNCTION_BODY */};

function hereOrThere() { //function statement
  return 'here';
}

alert(hereOrThere()); // alerts 'there'

function hereOrThere() {
  return 'there';
}

function hereOrThere() { //function statement
  return 'here';
}

function hereOrThere() {//申明前置了，但因为这里的申明和赋值在一起，所以一起前置
  return 'there';
}

alert(hereOrThere()); // alerts 'there'

var hereOrThere = function() { // function expression
  return 'here';
};

alert(hereOrThere()); // alerts 'here'

hereOrThere = function() {
  return 'there';
};

var hereOrThere；//申明前置了

hereOrThere = function() { // function expression
  return 'here';
};

alert(hereOrThere()); // alerts 'here'

hereOrThere = function() {
  return 'there';
};