How to use the functions of apply and call

Although apply and call can implement same function. However, there is a litter different between them. Please pay attention-to-look at the examples below:

Define an object person

1 person=function(name,age) {2this    . name=name; 3    this. age= age; 7 }89var pin=New//Create an object

After then, we need to define some functions (skating,running,eating) with different parameter s respectively.

1 functionSkating ()//It don ' t need any parameter2 {3Alert This. name+ "Like skating!");4 }5 6 functionRunning (distance)//It need 1 parameter7 {8Alert This. name+ "can only run" +distance+ "meters!");9 }Ten  One functionEating (FRUIT1,FRUIT2)//It need 2 paramters A { -Alert This. name+ "Like eating" +fruit1+ "and" +fruit2+ "!"); -}

Now, I'll use the Apply and call respectively.

// After using apply skating.apply (PIN); Running.apply (pin,[); Eating.apply (pin,["Apple", "Orange"]); Results respectively:pin like skating!  meters! Pin like eating apply and orange!

// After using the call Skating.call (PIN); Running.call (PIN,+), Eating.call (PIN,"apple", "orange"); Results respectively:pin like skating!  meters! Pin like eating apply and orange!

From the results above, we can know the differences between apply and call:

Same:

1. apply and call All Can make object pin implement Sakting , running and , respectively. Exactly, object pin own three new functions (sakting ,  RUNNING  and eating ).

2. The first parameter pin is the replace the key , this among three functions. So, when the three functions call the variable this.name, the key "This was not three functions T Hemselves but an object pin.

3. If the first paramter is null, the Global Object window would replace it.

4. If the function (such as skating) don ' t need any paramters, the apply and call is same.

Difference:

If the function need a parameter at least, the parameter should is a array using apply. For the call, without any constraints.