Arguments of Function

最新推荐文章于 2023-12-02 20:06:50 发布

原创最新推荐文章于 2023-12-02 20:06:50 发布 · 575 阅读

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#function #parameters #properties #each

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本文详细解释了JavaScript中函数的arguments参数是如何隐藏且自动传递的，包括如何获取传递的参数数量以及参数值。通过多个示例演示了arguments的使用方式。

There is the "arguments" parameter for each function which is hiddend and automaticly passed.

All the parameters passed through calling will all be pushed into "arguments". So we can get all passed parameters from it.

We can get the designed number of the function by calling ".length" of the function itself.

Demo0:None parameter passed

Source:

function ArgTest(a, b){
   var i, s = "The ArgTest function expected ";
   var numargs = arguments.length;     // 获取被传递参数的数值
   var expargs = ArgTest.length;       // 获取期望参数的数值
   s = "The desinged number of ArgTest Function's parameters:"+expargs;
   s += "\nThe real number of Passed parameters:"+numargs;
   for (i =0 ; i < numargs; i++){
   s += "\nArg[" + i + "]= " + arguments[i];
   }
   alert(s);
}
ArgTest();

Result:

Demo1:One parameter passed

Source:

function ArgTest(a, b){
   var i, s = "The ArgTest function expected ";
   var numargs = arguments.length;     // 获取被传递参数的数值
   var expargs = ArgTest.length;       // 获取期望参数的数值
   s = "The desinged number of ArgTest Function's parameters:"+expargs;
   s += "\nThe real number of Passed parameters:"+numargs;
   for (i =0 ; i < numargs; i++){
   s += "\nArg[" + i + "]= " + arguments[i];
   }
   alert(s);
}

ArgTest(1);

Result:

Demo2:Two parameter passed

Source:

function ArgTest(a, b){
   var i, s = "The ArgTest function expected ";
   var numargs = arguments.length;     // 获取被传递参数的数值
   var expargs = ArgTest.length;       // 获取期望参数的数值
   s = "The desinged number of ArgTest Function's parameters:"+expargs;
   s += "\nThe real number of Passed parameters:"+numargs;
   for (i =0 ; i < numargs; i++){
   s += "\nArg[" + i + "]= " + arguments[i];
   }
   alert(s);
}

ArgTest(1,2);

Result:

Demo3:Three parameters passed

Source:

function ArgTest(a, b){
   var i, s = "The ArgTest function expected ";
   var numargs = arguments.length;     // 获取被传递参数的数值
   var expargs = ArgTest.length;       // 获取期望参数的数值
   s = "The desinged number of ArgTest Function's parameters:"+expargs;
   s += "\nThe real number of Passed parameters:"+numargs;
   for (i =0 ; i < numargs; i++){
   s += "\nArg[" + i + "]= " + arguments[i];
   }
   alert(s);
}

ArgTest(1,2,3);

Result:

At the same time, we should know that "arguments" is not Array type.

We can check this by the following codes as using the inherition of properties theory :

Array.prototype.ptyProperty= 1;
function checkAgumentsType(){
    return arguments.ptyProperty;
}

s = new Array().ptyProperty;
s += "\n"+checkAgumentsType();
alert(s);

From this, we can get the point that "arguments" is not a Array instance.