函數(shù)語法
function 函數(shù)名(形參列表){
執(zhí)行代碼
}
函數(shù)的調(diào)用
function add (number1,number2){
var sum = number1 + number2;
return sum;
}
var a = add(3,4); //7
函數(shù)的參數(shù) 原始類型
實(shí)參小于形參個(gè)數(shù)
function add (number1,number2){//number1 = 3,number2 = undefined
var sum = number1 + number2;
return sum;
}
var a = add(3); //
實(shí)參大于形參個(gè)數(shù)
function add (number1,number2){
//number1 = 3,number2 = 4
var sum = number1 + number2;
return sum;
}
var a = add(3,4,5); //
實(shí)參有多個(gè)
function add (){
var length = arguments.length,
sum = 0,
paramenter;
for (var i = 0; i < length; i++) {
paramenter = arguments[i];
sum += paramenter;
}
return sum;
}
alert(add(3,4));
alert(add(3,4,5,6,7,8));
參數(shù)為對(duì)象類型 引用傳遞 值改變
function increment(person){
person.age += 1;
return person;
}
var jerry ={ name:'Jerry',age = 1; }
var x = increment(jerry);
作用域
this表示調(diào)用該函數(shù)的對(duì)象
作為對(duì)象屬性
構(gòu)造函數(shù)
原型
