Overview of JavaScript ES6 features

Post by dsp1234 » Mon, Oct 24, 2016, 8:05 PM UTC

BinaryIdiot wrote: post #140

dsp1234 wrote: post #132

Earlier quoted context omitted.

const x = Object.freeze({ y: { foo: 'bar' } }); x.y.foo = 'baz' console.log(x.y.foo) //baz immutablejs might be overkill, but not having, and using, a recursive freeze is going to bite a lot of people if the advice is just 'const + Object.freeze'.

> immutablejs might be overkill, but not having, and using, a recursive freeze is going to bite a lot of people if the advice is just 'const + Object.freeze'. No one should be trying to use a recursive freeze (if they are I would argue their data structure is poorly suited to be immutable). I'm not saying `const` + `Object.freeze()` gets you Immutablejs I'm saying it gets you, likely, what you want / need.

  const x = Object.freeze([
    {id: 1, value: 'foo'},
    {id: 2, value: 'bar'},
    {id: 3, value: 'baz'},
  ])

  ...

  //Bug in the code
  x[0].value = 'test'

Post by CGamesPlay » Mon, Oct 24, 2016, 8:14 PM UTC

AgentME wrote: post #103

The most interesting part about template strings was skipped over: tagged template literals. You can prefix a template string with a function which will get called with the list of string parts and the values passed in ${...} parts, and then it's up to the function to choose how to join the values up into the resulting string (or hell, you could make it return something besides a string if you want). The function can…

Post by [deleted] » Mon, Oct 24, 2016, 8:25 PM UTC

SHOwnsYou wrote: post #138

Meegul wrote: post #130

Earlier quoted context omitted.

It's spelled out pretty well in the article. But if you want another example, consider these two code blocks: var foo; var bar; { let foo = "hello"; var bar = "world"; } console.log(foo); console.log(bar); This produces: undefined world The reason being that the `let` statement restricted that variable to the block it was in (defined by the { and }). `var` declares the variable globally, allowing it to be accessed ou…

From the article-- let x = 'outer'; function test(inner) { if (inner) { let x = 'inner'; return x; } return x; // gets result from line 1 as expected } test(false); // outer test(true); // inner This makes it seem like let creates global variables. Why would you want to return a variable from outside the function? Doesn't that create massive overhead in terms of keeping track where variables are initially set? Easy t…

Post by CGamesPlay » Mon, Oct 24, 2016, 8:31 PM UTC

iamleppert wrote: post #163

"best practices": "use class instead of manipulating prototype directly" Who comes up with these "rules"? This is not a hard and fast rule. Manipulating the prototype of an object is not "dangerous". I'm sick and tired of some loud mouth saying something is dangerous without explaining why. WHY? Why it it dangerous? Don't talk at me. Provide me a sound reason and case to justify what you say. Talk is cheap. It makes…

Post by lmkg » Mon, Oct 24, 2016, 8:39 PM UTC

gotofritz wrote: post #170

abritinthebay wrote: post #91

Earlier quoted context omitted.

> Is it just me, or is Javascript (and more generally, all front end technology) more susceptible to these trivial holy wars? - Tabs vs spaces. - Vi vs Emacs - Weak vs strong typing - where to place {} in block statements - where to put commas No, programming in general is susceptible to these trivial holy wars.

Vi vs Emancs? Weak vs strong typing?? tabs vs spaces??? where did you get those?? The ONLY holy war in JS is the semi-colon one