implementation of if command in variables

Question

here is my code:

var a=false;
var b=false;
var c=true;
var d=false;
//
var x = a ? a : (b ? b : (c ? c: false)) ;
//
for(i=0;i<11;i++){
    document.write(x);
}

the inline if command check's which variable (a,b,c) is true then equal's x to that
and in the loop it will write that 10 times
there are two assumptions:

first: it will execute if command 10 times in loop to get final value of x
second: it will execute if command just one time just into x at first and in loop x will be just a variable containing true

which one is true?
thanks

exception run is not defined, question is hard to understand, what are you asking ? should "run" be "x" ? — john Smith, Sep 03 '14 at 13:15
JavaScript does not have lazy evaluation. Everything is evaluated immediately. Hope that helps. — Felix Kling, Sep 03 '14 at 13:17
This is a syntax error, the last conditional operator is missing its else part. — Bergi, Sep 03 '14 at 13:22
this is able too , but i'm asking for something like @Felix said — mk rowling, Sep 03 '14 at 13:26
Why not run the damn code and figure it out? For example, in the `for` loop, try setting `c = false`. Does `x` change? There's your answer. — Matt Burland, Sep 03 '14 at 13:35

john Smith · Accepted Answer · 2014-09-03T13:41:17.467

it contains a typo anyway, to be sure it should rather look like :

var x = a ? a : (b ? b : (c ? c: false)) ;

so you could test it like:

var a=false;
var b=false;
var c=false;
var d=false;

var x = a ? a : (b ? b : (c ? c: "everything false")) ;


function runTest(){
    for(i=0;i<11;i++){
        console.log(x);
    }   
}

so when you runTest() is will log "everything false" changing the variable b=true in console, e.g without refreshing the page, so your scenario and runTest() again it will still prin "everything false"

so the answer is

once x is assigned the expression, x IS the result of the expression and not the expression itself, and when you print x some later it still is the same result, even if the result of the expression now would be different ( because some gobal variables changed )

to let x always be "up to date" make it a function

x = function () {
  return a ? a : (b ? b : (c ? c: false)) ;
}

then it would evaluate on every call

implementation of if command in variables

1 Answers1