JavaScript Tips

tips.js

// Verify that a given argument is a number
function isNumber(n){
    return !isNaN(parseFloat(n)) && isFinite(n);
}

//  Get the max or the min in an array of numbers
var  numbers = [5, 458 , 120 , -215 , 228 , 400 , 122205, -85411]; 
var maxInNumbers = Math.max.apply(Math, numbers); 
var minInNumbers = Math.min.apply(Math, numbers);

// Truncate an array using length
var myArray = [12 , 222 , 1000 , 124 , 98 , 10 ];  
myArray.length = 4; // myArray will be equal to [12 , 222 , 1000 , 124]

//  Rounding number to N decimal place
var num =2.443242342;
num = num.toFixed(4);  // num will be equal to 2.4432

// Floating point problems
0.1 + 0.2 === 0.3 // is false , is  0.30000000000000004
9007199254740992 + 1 // is equal to 9007199254740992  
9007199254740992 + 2 // is equal to 9007199254740994