let

问题 I am trying to get Firefox to run a Promise in ES6 but run into the 'let' keyword triggering an error; SyntaxError: let is a reserved identifier Changing the script tag to include; type="application/javascript;version=1.7" did not work, so I am seeking to Transpile the code. My situation is that there is nothing being used except a text editor. No NPM, not Node or Angular, no Visual Studio, nothing. So when I investigated the Compilers, I saw no option to let me Transpile this code without

问题 I want to update a record syntax with a change in one field so i did something like: let rec = rec{field = 1} But I've noticed that i can't print rec anymore, means the compiler seems to get into an infinite loop when i try. so i have tried doing: let a = 1 -- prints OK let a = a -- now i can't print a (also stuck in a loop) So i can't do let a = a with any type, but i don't understand why, and how should i resolve this issue. BTW: while doing: let b = a {...record changes..} let a = b works,

问题 I want to use Lazy initialization for some of my properties in Swift. My current code looks like this: lazy var fontSize : CGFloat = { if (someCase) { return CGFloat(30) } else { return CGFloat(17) } }() The thing is that once the fontSize is set it will NEVER change. So I wanted to do something like this: lazy let fontSize : CGFloat = { if (someCase) { return CGFloat(30) } else { return CGFloat(17) } }() Which is impossible. Only this works: let fontSize : CGFloat = { if (someCase) { return

问题 I am taking an online JS course and the instructor used the syntax : let = names = ["Bob","Tim","Larry"] . I am convinced that was an accident, but somehow allowed by the JS environment he was using. What he ended up doing (probably by accident) was assign the array to the "names" variable, which assigned it to the "let" variable. My question: why is this not an error? Why can "let" be used as an variable? We know "let" is a keyword. Or is it just something they haven't outlawed yet? You can

问题 I found many topics explaining this problem, on how I can fix the following code by using var, like this one http://conceptf1.blogspot.com/2013/11/javascript-closures.html or this one JavaScript closure inside loops – simple practical example. But I really can't understand why it is not working when using var and working when using let. var funcs = []; for (var i = 0; i < 3; i++) { // let's create 3 functions funcs[i] = function() { // and store them in funcs console.log("My value: " + i); //

问题 I have read the rspec docs and have searched a number of other places but I am having a difficult time grasping the difference between Rspec's let and let! I've read that let isn't initialized until it's needed and that its value is only cached per example. I've also read that let! forces the variable into immediate existence, and forces invocation for each example. I guess since I'm new, I'm having a difficult time seeing how this relates to the following examples. Why does :m1 need to be

问题 In SAS, is it possible to refer a %let statement to a value located in a database? For instance, the value of my n in %let n=50 depends on some value calculated in one of my databases, e.g., first row plus first column. And since that value gets modified 100 times in my loop I don't want to manually enter that value. 回答1: There's several ways to do this. Here's two: proc sql; select a+b into :n from your_table where some_condition; quit; This populations a macro variable, &n , with the sum of

问题 I'm not sure why but it seems that I can't call the let or const variables if I declare them in an if/else statement. if (withBorder) { const classes = `${styles.circularBorder} ${styles.dimensions} ${styles.circularPadding} row flex-items-xs-middle flex-items-xs-center`; } else { const classes = `${styles.dimensions} ${styles.circularPadding} row flex-items-xs-middle flex-items-xs-center`; } return ( <div className={classes}> {renderedResult} </div> ); If I use this code it says that classes

问题 I have been playing with ES6 for a while and I noticed that while variables declared with var are hoisted as expected... console.log(typeof name); // undefined var name = "John"; ...variables declared with let or const seem to have some problems with hoisting: console.log(typeof name); // ReferenceError let name = "John"; and console.log(typeof name); // ReferenceError const name = "John"; Does this mean that variables declared with let or const are not hoisted? What is really going on here?

问题 I am working (joyfully) working through the Introduction to Emacs Lisp Programming and have solved the first 8.7 Searching Exercise. It states, Write an interactive function that searches for a string. If the search finds the string, leave point after it and display a message that says “Found!”. My solution is (defun test-search (string) "Searches for STRING in document. Displays message 'Found!' or 'Not found...'" (interactive "sEnter search word: ") (save-excursion (beginning-of-buffer)