Useful JS Tips

#60 - Three useful hacks

2016-10-28 by @leandrosimoes

Getting array items from behind to front

If you want to get the array items from behind to front, just do this:

var newArray = [1, 2, 3, 4];

console.log(newArray.slice(-1)); // [4]
console.log(newArray.slice(-2)); // [3, 4]
console.log(newArray.slice(-3)); // [2, 3, 4]
console.log(newArray.slice(-4)); // [1, 2, 3, 4]

Short-circuits conditionals

If you have to execute a function just if a condition is true, like this:

if(condition){
    dosomething();
}

You can use a short-circuit just like this:

condition && dosomething();

Set variable default values using “||”

If you have to set a default value to variables, you can simple do this:

var a;

console.log(a); //undefined

a = a || 'default value';

console.log(a); //default value

a = a || 'new value';

console.log(a); //default value
<<返回目录