I'm wondering if there's a shorter way to write this:
var x = 1;
if(y != undefined) x = y;
I initially tried x = y || 1, but that didn't work. What's the correct way to go about this?
This question is related to
javascript
shorthand
var x = y !== undefined ? y : 1;
Note that var x = y || 1; would assign 1 for any case where y is falsy (e.g. false, 0, ""), which may be why it "didn't work" for you. Also, if y is a global variable, if it's truly not defined you may run into an error unless you access it as window.y.
As vol7ron suggests in the comments, you can also use typeof to avoid the need to refer to global vars as window.<name>:
var x = typeof y != "undefined" ? y : 1;
Appears you are having 'y' default to 1: An arrow function would be useful in 2020:
let x = (y = 1) => //insert operation with y here
Let 'x' be a function where 'y' is a parameter which would be assigned a default to '1' if it is some null or undefined value, then return some operation with y.
Here is a way to do it that works, but may not be best practise for any language really:
var x,y;
x='something';
y=1;
undefined === y || (x = y);
alternatively
undefined !== y && (x = y);
Another way to write it shortly
bePlanVar = !!((bePlanVar == false));
// is equivalent to
bePlanVar = (bePlanVar == false) ? true : false;
// and
if (bePlanVar == false) {
bePlanVar = true;
} else {
bePlanVar = false;
}
Other way is using short-circuit:
x = (typeof y !== 'undefined') && y || 1
Although I myself think that ternary is more readable.
You can try if/else this shorthand method:
// Syntax
if condition || else condition
// Example
let oldStr = "";
let newStr = oldStr || "Updated Value";
console.log(newStr); // Updated Value
// Example 2
let num1 = 2;
let num2 = num1 || 3;
console.log(num2); // 2 cause num1 is a truthy
y = (y != undefined) ? y : x;
The parenthesis are not necessary, I just add them because I think it's easier to read this way.
Source: Stackoverflow.com