The difference between call () and apply ()

<span id="Label3"></p><p><p>call <strong>method:</strong><br>Syntax: call ([thisobj[,arg1[, arg2[, [,. argN]]])<br>Definition: invokes one method of an object, replacing the current object with another Object.<br>Description<br>The call method can be used to invoke a method in place of another object. The call method can change the object context of a function from the initial context to a new object specified by thisobj.<br>If the thisobj parameter is not provided, then the Global object is used as the thisobj.<br><br><strong>Apply Method:</strong><br>Syntax: Apply ([thisobj[,argarray]])<br>Definition: a method of applying an object that replaces the current object with another Object.<br>Description<br>If Argarray is not a valid array or is not a arguments object, it will result in a TypeError.<br>If none of the Argarray and thisobj parameters are provided, then the Global object is used as a thisobj and cannot be passed any Parameters.</p></p><p><p></p></p><p><p>Instance:</p></p> <ol class="dp-j" start="1"> <ol class="dp-j" start="1"> <li>function Add (a, b)</li> <li>{</li> <li>Alert (a+b);</li> <li>}</li> <li>function Sub (a, b)</li> <li>{</li> <li>Alert (a-b);</li> <li>}</li> <li></li> <li>Add.call (sub,<span class="number">3,<span class="number">1); </span></span></li> <li><span class="number">The meaning of this example is to replace sub,add.call (sub,3,1) = = Add (3,1) with add, so the result is: alert (4); Note: the function in JS is actually an object, and the function name is a reference to a function object.</span></li> </ol> </ol><p><p></p></p> <ol class="dp-j" start="1"> <li><li>function Animal () {</li></li> <li><li><span class="keyword">this.name = <span class="string">"Animal"; </span></span></li></li> <li><li><span class="keyword">This.showname = function () {</span></li></li> <li><li>Alert (<span class="keyword">this.name); </span></li></li> <li><li>}</li></li> <li><li>}</li></li> <li><li></li></li> <li><li>function Cat () {</li></li> <li><li><span class="keyword">this.name = <span class="string">"Cat"; </span></span></li></li> <li><li>}</li></li> <li><li></li></li> <li><li>var animal = <span class="keyword">new Animal (); </span></li></li> <li><li>var cat = <span class="keyword">New Cat (); </span></li></li> <li><li></li></li> <li><li><span class="comment">Using the call or Apply method, the ShowName () method that originally belonged to the animal object is given to the object cat.</span></li></li> <li><li><span class="comment">The input result is "Cat"</span></li></li> <li><li>Animal.showName.call (cat,<span class="string">","); </span></li></li> <li><li><span class="comment">Animal.showName.apply (cat,[]);</span></li></li> </ol><p><p><span class="comment">Another example:</span></p></p><p><p>function Animal () {</p></p><p><p><span class="keyword">THIS.name = <span class="string">"Animal"; </span></span></p></p><p><p><span class="keyword">This.showname = function () {</span></p></p><p><p>Alert (<span class="keyword">this.name); </span></p></p><p><p>}</p></p><p><p>}</p></p><p><p>function Cat () {</p></p><p><p><span class="keyword">THIS.name = <span class="string">"Cat"; </span></span></p></p><p><p>}</p></p><p><p>var animal = <span class="keyword">new Animal (); </span></p></p><p><p>var cat = <span class="keyword">New Cat (); </span></p></p><p><p><span class="comment">Using the call or Apply method, the ShowName () method that originally belonged to the animal object is given to the object cat.</span></p></p><p><p><span class="comment">The input result is "Cat"</span></p></p><p><p>Animal.showName.call (cat,<span class="string">",");  </span> <span class="comment">//animal.showname.apply (cat,[]); </span></p></p><p><p><span class="comment" style="color: #ff0000;">Call means to put the animal method on the cat, the original cat is no showname () method, now is to put animal showname () method on the cat to execute, so this.name should be cat</span></p></p><p><p><span class="comment">To implement Inheritance:</span></p></p> <ol class="dp-j" start="1"> <li><li>function Animal (name) {</li></li> <li><li><span class="keyword">this.name = name; </span></li></li> <li><li><span class="keyword">This.showname = function () {</span></li></li> <li><li>Alert (<span class="keyword">this.name); </span></li></li> <li><li>}</li></li> <li><li>}</li></li> <li><li></li></li> <li><li>function Cat (name) {</li></li> <li><li>Animal.call (this<span class="keyword">, name); </span></li></li> <li><li>}</li></li> <li><li></li></li> <li><li>var cat = <span class="keyword">New Cat (<span class="string">"Black cat"); </span></span></li></li> <li><li>Cat.showname ();</li></li> </ol><p><p><span style="color: #ff0000;">Animal.call (this) means that the Animal object is used instead of the this object, so there is no Animal of all the properties and methods in cat, and the Cat object can directly invoke the Animal method and Properties.</span></p></p><p><p></p></p><p><p><span class="comment">To implement multiple inheritance:</span></p></p> <ol class="dp-j" start="1"> <li><li>function Class10 ()</li></li> <li><li>{</li></li> <li><li><span class="keyword">this.showsub = function (a, b)</span></li></li> <li><li>{</li></li> <li><li>Alert (a-b);</li></li> <li><li>}</li></li> <li><li>}</li></li> <li><li></li></li> <li><li>function Class11 ()</li></li> <li><li>{</li></li> <li><li><span class="keyword">this.showadd = function (a, b)</span></li></li> <li><li>{</li></li> <li><li>Alert (a+b);</li></li> <li><li>}</li></li> <li><li>}</li></li> <li><li></li></li> <li><li>function Class2 ()</li></li> <li><li>{</li></li> <li><li>Class10.call (this<span class="keyword">); </span></li></li> <li><li>Class11.call (this<span class="keyword">); </span></li></li> <li><li>}</li></li> </ol><p><p><span style="color: #ff0000;">simple, using two call to achieve multiple inheritance</span><br><span style="color: #ff0000;">of course, JS inheritance There are other methods, such as the use of prototype chain, this is not part of the scope of this article, just here to illustrate the use of Call. Said call, of course, and apply, These two methods are basically a meaning, the difference is that the second parameter of call can be any type, and the second argument of apply must be an array, or it can be arguments</span></p></p><p><p></p></p><p><p>The difference between call () and apply ()</p></p></span>