用window.globalVariableName。 12vara =1;3functiontest(){4alert(window.a);//a为1,这里的a是全局变量哦!5vara=2;//局部变量a在这行定义6alert(a);//a为2,这里的a是局部变量哦!7}8test();9alert(a);//a为1,这里并不在function scope内,a的值为全局变量的值10...
先看第一句：At the top level of aScript, function declarations are treated like var declarations ...
available as a global in Node.js 24. Contributed by Yagiz Nizipli and Daniel Lemire in #56452. Support for the zstd compression algorithm Node.js now includes support for the Zstandard (zstd) compression algorithm. Various APIs have been added to the node:zlib module for both compression and...
As a simple example, imagine having a “debug mode” in your program that is controlled by a global variable (flag) calledDEBUG. You’d want to check if that variable was declared before performing a debug task like logging a message to the console. A top-level globalvar DEBUG = truedec...
// Check if variable is equal to valueif(username==="sammy_shark"){console.log(true);} 输出: 代码语言:javascript 复制 true 如前所述,变量可以用来表示任何JavaScript数据类型。在本例中,我们将使用字符串、数字、对象、布尔值和null值声明变量。
and they can even be cleared out like a regular variable. The difference between a regular variable and a global variable comes down to their scope. When you create a variable in a JavaScript file, that variable only exists in the scope that it was declared in. Now what do I mean by ...
However, what if we want to export this function directly, and not as the property of some object? We can overwrite exports to do this, but we must not treat it as a global variable then: // a.jsmodule.exports=function(user, password, done) { ... } ...
The files are parsed in the same global scope, that is, a reference from a file to some variable/function declared in another file will be matched properly. If no input file is specified, UglifyJS will read from STDIN. If you wish to pass your options before the input files, separate ...
functionfoo(arg){bar="this is a hidden global variable";} bar就被挂到window上了,如果bar指向一个巨大的对象,或者一个DOM节点,就会代码内存隐患 另一种不太明显的方式是构造函数被直接调用(没有通过new来调用): 代码语言:javascript 复制 functionfoo(){this.variable="potential accidental global";}// Foo...
functionfoo(arg){bar="this is a hidden global variable";}// 上面的函数等价于functionfoo(arg){window.bar="this is an explicit global variable";} 所以,你调用完了函数以后,变量仍然存在,导致泄漏. 如果不注意this的话,还可能会这么漏: 代码语言:javascript ...