js里什么叫实例,什么叫实例化

JavaScript07

js里什么叫实例,什么叫实例化,第1张

把一个类,变成实际存在的一个"例子",叫实例化. 说白了,如: "人"是一个概念,相当于一个"类" "小明"是一个具体存在的"人"的例子,相当于一个"实例". 把"人"变成"小明"的过程,就是"人的实例化".

main.html做个导航栏,right.html做radiobutton的五个input type="text",left.html做textbox的五个,用iframe将right和left放到所需位置,设置visibility为hidden,点击后用JS改变其值为visible,保存的实现用sample.js,就是改变这些input的defaultValue为输入的内容

本js代码通过对js对象进行各方面的比较来判断两个对象是否相等

cmp = function( x, y ) {

// If both x and y are null or undefined and exactly the same

if ( x === y ) {

return true

}

// If they are not strictly equal, they both need to be Objects

if ( ! ( x instanceof Object ) || ! ( y instanceof Object ) ) {

return false

}

//They must have the exact same prototype chain,the closest we can do is

//test the constructor.

if ( x.constructor !== y.constructor ) {

return false

}

for ( var p in x ) {

//Inherited properties were tested using x.constructor === y.constructor

if ( x.hasOwnProperty( p ) ) {

// Allows comparing x[ p ] and y[ p ] when set to undefined

if ( ! y.hasOwnProperty( p ) ) {

return false

}

// If they have the same strict value or identity then they are equal

if ( x[ p ] === y[ p ] ) {

continue

}

// Numbers, Strings, Functions, Booleans must be strictly equal

if ( typeof( x[ p ] ) !== "object" ) {

return false

}

// Objects and Arrays must be tested recursively

if ( ! Object.equals( x[ p ], y[ p ] ) ) {

return false

}

}

}

for ( p in y ) {

// allows x[ p ] to be set to undefined

if ( y.hasOwnProperty( p ) &&! x.hasOwnProperty( p ) ) {

return false

}

}

return true

}

使用:

objA={

a:'123',

b:'456'

}

objB={

a:'123',

b:'000'

}

var isEqual= cmp(objA, objB)

console.log(isEqual) // false 不相同