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《编写可维护的JavaScript》读书笔记
Page88 检测
检测原始值
�//检测字符串
if(typeof name === "string"){
}
//检测数字
if(typeof coutn === "number"){
}
//检测布尔值
if(typeof found === "boolean" && found){
}
//检测 undefined
if(typeof MyApp === "undefined"){
}
//检测 null
var element = document.getElementById('my_div');
if(element !== null){
}
检测在引用值
//检测日期
if(value instanceof Date){
}
//检测正则表达式
if(value instanceof RegExp){
}
//检测 Error
�if(value instanceof Error){
}
检测函数
var myFun = function(){};
console.log(typeof myFun === "function");
/*
用typeof来检测函数有一个限制,在IE8和更早版本的IE浏览器中,
检测DOM节点中的函数都会返回“object”,而不是"function"
*/
//检测 DOM 方法
if("querySelectorAll" in document){
}
检测数组
function isArray(value){
return Object.prototype.toString.call(value) === "[object Array]";
}
检测属性
var obj = {
count : 0
};
if("count" in obj){
}
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