JavaScript patterns 笔记（一） 全局变量
myglobal ="hello"; // antipattern
console.log(myglobal); //"hello"
console.log(window.myglobal); //"hello"
console.log(window["myglobal"]);// "hello"
console.log(this.myglobal); //"hello"
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function sum(x, y) {
// antipattern: implied global
result = x + y;
return result;
function sum(x, y) {
var result = x + y;
return result;
// antipattern, do not use
function foo() {
var a = b = 0;
// ...
functionfoo() {
var a, b;
// ...
a = b = 0;// both local
}
// definethree globals
varglobal_var = 1;
global_novar= 2; // antipattern
(function (){
global_fromfunc= 3; // antipattern
}());
// attempt to delete
deleteglobal_var; // false
delete global_novar; // true
delete global_fromfunc; // true
// test the deletion
typeof global_var; //"number"
typeof global_novar; //"undefined"
typeofglobal_fromfunc; // "undefined"
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var global =(function () {
return this;
}());
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