strict

问题 I wasn't able to find anything helpful through google, so: My Dart webapplication worked perfectly. Next time I opened Darteditor and (without changing anything) ran it again, Darteditor showed the Error Breaking on exception: Strict get failed, invalid object. This Error doesn't always show up and even when it does, the App still functions. Darteditor doesn't give me any hit where that Error occurs, because the debugger claims some source not to be available. Does anyone know why/when this

问题 This question is a copy of “Use Strict” needed in a TypeScript file? There are some answers, but it is not clear for what does "use strict" statement in TypeScript, when tsc shoes me strict mode errors without this statement. But decided to ask as separated question aw well. I am using TypeScript 1.6 and for me it is not clear what does "use strict" statement add in TypeScript? Using "use strict"; statement looks like double check. Since tsc shows strict mode errors without this statement.

问题 I get the basic idea about this not being in a method when in strict mode outlined here, but it gets a bit erudite, to be honest. So, in more prosaic terms: I have a handler like so: $('.myClass').one('keyup', function() { var $this = $(this); etc etc }); I want to change it to this: function myFunction () { var $this = $(this); etc etc }; $('.myClass1').one('keyup', myFunction); $('.myClass2').one('keyup', myFunction); etc It doesn't like it because in strict mode because I'm using this

问题 John Resig wrote: Finally, a long-standing (and very annoying) bug has been resolved: Cases where null or undefined is coerced into becoming the global object. Strict mode now prevents this from happening and throws an exception instead. (function(){ ... }).call( null ); // Exception what bug is he referring to? 回答1: Basically, you are using the call() method from Function.prototype , which by default takes scope as the first parameter. If execution scope is undefined or null , it defaults to

问题 Here is my code that seems to indicate that the answer is yes - http://jsfiddle.net/4nKqu/ var Foo = function() { 'use strict' return { foo: function() { a = 10 alert('a = ' + a) } } }() try { Foo.foo() } catch (e) { alert(e) } Could you please cite the statements from the standard that clarifies that 'use strict' is automatically applied to all closures and functions defined within a function to which we have applied 'use strict' ? 回答1: The relevant part of the spec: http://www.ecma

问题 Today I run into a weird JS bug, working with const inside a try/catch block, and I'd like to better understand what is causing it. Let's look at a code example, that is worth more than a thousand words: try { const FOO = 'bar'; console.log('inside:', FOO); } catch (e) {} console.log('outside:', FOO); This will log: inside: bar outside: bar If we switch to "strict mode" though: 'use strict'; try { const FOO = 'bar'; console.log('inside:', FOO); } catch (e) {} console.log('outside:', FOO); Now

问题 JavaScript doesn't care if your Strings are double-quoted "double" or single-quoted 'single' . Every example of ECMAScript 5's strict mode has it enabled by "use strict" in double-quotes. Can I do the following (single-quotes): alert(function(){ 'use strict'; return !this; }()); This will return true if Strict mode is enabled, and false if it is not. 回答1: For you, without using a browser that supports strict mode: A Use Strict Directive is an ExpressionStatement in a Directive Prologue whose

问题 What's the difference, from the interpreter's POV, between the following the following programs: #!/usr/bin/perl -w use strict; for (1..10000000) { my $jimmy = $_**2; } and #!/usr/bin/perl -w use strict; my $jimmy; for (1..10000000) { $jimmy = $_**2; } "time" reports for the first program: real 0m1.519s user 0m1.513s sys 0m0.004s and for the second: real 0m1.023s user 0m1.012s sys 0m0.002s 回答1: The my declaration in Perl has two primary effects; a compile-time one (wherein it allocates a slot

问题 I have a project with literally hundreds of JavaScript source files. I am wondering what is the best way to enable the strict mode for the project? I understand the consequences of this action and I am only looking for advice regarding the deployement of this feature. Placing "use strict" in every file does not seem fun. 回答1: Well, I'm not clear on the context your javascript files will be used in, however say the context is a dynamic web application where various page files, javascript files

问题 Besides use strict , which other use directives are there? 回答1: Some more examples that can be in the “directive prologue” (a section potentially usable by JavaScript engines): 'use strict'; 'use asm'; Mozilla's asm.js is a subset of the language, geared towards crunching numbers. 'use stricter'; Google's SoundScript. For fast OOP Has also some modes like: 'use stricter+types'; http://www.2ality.com/2015/02/soundscript.html 'use babel'; Used in Atom.io. (Was previously: 'use 6to5'; ) A tweet