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This article brings you an introduction to the usage of the Arguments object in javaScript. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.
1. Figure out what arguments are
“arguments is an array-like object corresponding to the parameters passed to the function.
arguments object is Local variables available in all (non-arrow) functions. You can reference a function's arguments within a function using the arguments object. This object contains each argument passed to the function, with the first argument at index 0."
First of all, it is an array-like object. The result of typeof arguments is undoubtedly "object". Note that the result is of string type. Next, Object.prototype.toString.call(arguments) is called, and the result is "[object Arguments]" that has never been seen before.
2. Convert to array
1.Array’s silce method
Array.prototype.slice.call(arguments)
2.Array.from
let re = Array.from(arguments)
3. Expansion operator
let re = [...arguments]
3. From arguments to class array
The class array must have a length attribute and an index attribute. The following is explained with the code:
let obj = { "0": 'a', "1": 'b', "2": 'c', length: 3, "push": Array.prototype.push, "splice": Array.prototype.splice } obj.push('d') console.log(obj)
The result is:
The actual execution process is equivalent to:
obj[obj.length] = 'd'; obj.length++;
4. Written test questions
var length = 10; function fn(){ console.log(this.length) } var obj = { length: 5, getF: function(fn) { fn(); arguments[0](); } } obj.getF(fn);
What we examined were the arguments and this pointing question. I answered 5 1, but the actual result was 10 1. This is my first time writing an article, I hope it will be helpful to you.
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