1、this指向、闭包、全局/局部变量

js javascript">js-keyword">var w=js-number">100;
js-function">js-keyword">function js-title">f1js-params">(){
    js-function">js-keyword">function js-title">f2js-params">(){  js-comment">//严格来说不算闭包，并没有调用局部变量；
        document.write(js-keyword">this.w);
    }
    js-keyword">return f2;
}
f1()();  js-comment">//100 ,this指向问题：window调用f2所以this指向window,this.w查找全局中的w

js-comment">// ---------------分割线------------------

js-keyword">var w=js-number">100;
js-function">js-keyword">function js-title">f1js-params">(){
    js-keyword">var w=js-number">101; js-comment">//此处的w为局部变量w
    js-function">js-keyword">function js-title">f2js-params">(){
        document.write(js-keyword">this.w);
    }
    js-keyword">return f2;
}
f1()();  js-comment">//100  ,this指向问题：window调用f2所以this指向window,this.w查找全局中的w，并没有涉及闭包中的f2调用f1的局部变量

js-comment">// ---------------分割线------------------

js-keyword">var w=js-number">100;
js-function">js-keyword">function js-title">f1js-params">(){
    js-keyword">var w=js-number">101; js-comment">//此处的w为局部变量w
    js-function">js-keyword">function js-title">f2js-params">(){
        document.write(w);
    }
    js-keyword">return f2;
}
f1()();  js-comment">//101  ,闭包问题：闭包f2调用父函数f1中的局部变量w

js-comment">// ---------------分割线------------------

js-keyword">var w=js-number">100;
js-function">js-keyword">function js-title">f1js-params">(){
    w=js-number">101;  js-comment">//全局变量,当f1执行时，会给外部的全局变量w重新复制为101
    js-function">js-keyword">function js-title">f2js-params">(){
        document.write(js-keyword">this.w);
    }
    js-keyword">return f2;
}
f1()(); js-comment">//101  ,this指向问题：window调用f2所以this指向window,this.w查找全局中的w，而全局变量w被f1执行时重新复制为101

js-comment">// ---------------分割线------------------

js-keyword">var w=js-number">100;
js-function">js-keyword">function js-title">f1js-params">(){
    js-keyword">this.w=js-number">102;   js-comment">//f1执行时，window调用f1，this指向window,所以给全局变量w重新赋值
    js-function">js-keyword">function js-title">f2js-params">(){
        document.write(js-keyword">this.w);
    }
    js-keyword">return f2;
}
f1()();  js-comment">//102  ,this指向问题：window调用f2所以this指向window,this.w查找全局中的w