How to handle javascript variable scopes in different browsers _ javascript skills

Code 1. About prototype: prototype is a feature of javascript, not the famous prototype framework:

<Script type = "text/javascript"> var string = "hello world"; try {alert (string. phone ();} catch (e) {alert (e);} String. prototype. phone = function () {return "159-10957151";} alert (string. phone (); script
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2. Regarding the variable scope, different processing methods for js from IE and firefox, there are several examples here, some of which are notes that were originally viewed elsewhere, some of which were mine by myself.
2.1

<Script type = "text/javascript"> var deep_thought = {the_answer: 42, ask_question: function () {return this. the_answer ;}}; var the_meaning = deep_thought.ask_question (); alert (the_meaning); script
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2.2

<Script type = "text/javascript"> function test_this () {return this;} var I _wonder_what_this_is = test_this (); alert (I _wonder_what_this_is); // result: [object window]; script
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2.3:

<Script type = "text/javascript"> function click_handler () {alert (this); // pop-up window object} script... <button id = 'thebutton 'onclick = 'click _ handler () '> click me! </Button>
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2.4

<Script type = "text/javascript"> function click_handler (obj) {alert (obj); // result: [object HTMLButtonElement]} script... <button id = 'thebutton 'onclick = 'click _ handler (this) '> click me! </Button>
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2.5

<Button id = 'thebutton 'onclick = 'click _ handler (this) '> click me! </Button> <script type = "text/javascript"> function BigComputer (answer) {this. the_answer = answer; this. ask_question = function () {alert (this. the_answer) ;}} function addhandler () {var deep_thought = new BigComputer (42), the_button = document. getElementById ('thebutton'); the_button.onclick = deep_thought.ask_question;} window. onload = addhandler; // result [undefined] script
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2.6

<Button id = 'thebutton 'onclick = 'click _ handler (this) '> click me! </Button> <script type = "text/javascript"> function BigComputer (answer) {var self = this; self. the_answer = answer; self. ask_question = function () {alert (self. the_answer) ;}} function addhandler () {var deep_thought = new BigComputer (42), the_button = document. getElementById ('thebutton'); the_button.onclick = deep_thought.ask_question;} window. onload = addhandler; // result [42] script
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2.7

<Button id = 'thebutton 'onclick = 'click _ handler (this) '> click me! </Button> <script type = "text/javascript"> function btn_click () {alert (this);} function addhandler () {the_button = document. getElementById ('thebutton'); the_button.onclick = btn_click;} window. onload = addhandler; // result [undefined] script
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2.8

<Button id = 'thebutton 'onclick = 'click _ handler (this) '> click me! </Button> <script type = "text/javascript"> function real_func () {alert (this);} function btn_click () {setTimeout (real_func, 100 );} function addhandler () {the_button = document. getElementById ('thebutton'); the_button.onclick = btn_click;} window. onload = addhandler; // result [undefined] script
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2.9

<Button id = 'thebutton 'onclick = 'click _ handler (this) '> click me! </Button> <script type = "text/javascript"> Function. prototype. bind = function (obj) {var method = this, temp = function () {return method. apply (obj, arguments) ;}; return temp;} var real_func = function () {alert (this) ;}function btn_click () {setTimeout (real_func.bind (this ), 100);} function addhandler () {the_button = document. getElementById ('thebutton'); the_button.onclick = btn_click;} window. onload = addhandler; // result [undefined] script
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2.10

Script // ** variables need to be defined alert (document); // [object HTMLdocument] alert(registry.doc ument); // [object HTMLdocument] alert (window. face); // pretty var face = "pretty"; alert (face); // pretty alert (window. face); // pretty alert (window. sock); // undefined alert (sock); // ERROR: sock not defined script
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2.11

<Script type = "text/javascript"> function method () {var window ={}; alert (window. location);} alert (window. location); method (); alert (window. location); script
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2.12

<Script type = "text/javascript"> var window ={}; // ERROR: invalid value assignment! // This works in IE, but throw an Exception in firefox alert (window. location); script
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2.13

<Script type = "text/javascript">/** this is a very annoying piece of code. You can disable alert */window. alert ("hello world"); window. alert = function (str) {document. write (str) ;}; alert ("hello world"); window. alert ("hello world"); script
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2.14:

Note the differences between the results of these three html files.
A.html:

<Script type = "text/javascript"> alert (sock); function sock () {alert ("function sock executed! ");} Alert (sock); script
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B .html:

<Script type = "text/javascript"> alert (sock); var sock = function () {alert ("function sock executed! ");} Alert (sock); script
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C.html:

<Script type = "text/javascript"> // "undefined" is not displayed here. // It is a bit eccentric! Alert (sock); script
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2.15

Let's take a look at the differences between IE and firefox:

<Script type = "text/javascript"> Object. prototype. hello = function () {alert ("hello") ;}window. hello (); script
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