Javascript – Page 3 – Gain More Knowledge

Code of the Day: Chop up an array into groups using Underscore.js

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Shrink an array into a group of smaller arrays using underscore.js



// Make sure to include underscore.js 
_.mixin({
    chunk : function (array, unit) {
        if (!_.isArray(array)) return array;
        unit = Math.abs(unit);
        var results = [],
        length = Math.ceil(array.length / unit);
 
        for (var i = 0; i < length; i++) {
            results.push(array.slice( i * unit, (i + 1) * unit));
        }
        return results;
    }
});
// Make sure to include underscore.js 
_.mixin({
    chunk : function (array, unit) {
        if (!_.isArray(array)) return array;
        unit = Math.abs(unit);
        var results = [],
        length = Math.ceil(array.length / unit);

        for (var i = 0; i < length; i++) {
            results.push(array.slice( i * unit, (i + 1) * unit));
        }
        return results;
    }
});

Example:



JSON.stringify( _.chunk([1,2,3,4,5,6,7,8,9], 2) ); 
// returns "[[1,2],[3,4],[5,6],[7,8],[9]]"
JSON.stringify( _.chunk([1,2,3,4,5,6,7,8,9], 2) ); 
// returns "[[1,2],[3,4],[5,6],[7,8],[9]]"

Here’s the same thing without using Underscore.js



var chunk = function (array, unit) {
	if (typeof array !== "object")
		return array;
	unit = Math.abs(unit);
	var results = [],
	length = Math.ceil(array.length / unit);
 
	for (var i = 0; i < length; i++) {
		results.push(array.slice(i * unit, (i + 1) * unit));
	}
	return results;
}
var chunk = function (array, unit) {
	if (typeof array !== "object")
		return array;
	unit = Math.abs(unit);
	var results = [],
	length = Math.ceil(array.length / unit);
	
	for (var i = 0; i < length; i++) {
		results.push(array.slice(i * unit, (i + 1) * unit));
	}
	return results;
}

Larry Battle

I love to program, and discover new tech. Check out my <a href="http://stackoverflow.com/users/527776/larry-battle">stackoverflow</a> and <a href="https://github.com/LarryBattle">github</a> accounts.

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Code of the day – FizzBuzz in Javascript

FizzBuzz Test

Write a program that prints the numbers from 1 to 100. But for multiples of three print “Fizz” instead of the number and for the multiples of five print “Buzz”. For numbers which are multiples of both three and five print “FizzBuzz”.

—c2.com

Here’s my solution:
Test Driven Development Approach



// TDD Readable
var getFizzBuzzStatements = function (len) {
	var arr = [],
	str = "";
	for (var i = 1; i <= len; i++) {
		str = (i % 3) ? "" : "Fizz";
		str += (i % 5) ? "" : "Buzz";
		arr.push(str||i);
	}
	return arr;
};
var fizzBuzz = function () {
	console.log(getFizzBuzzStatements(100).join("\n"));
};
fizzBuzz();
// TDD Readable
var getFizzBuzzStatements = function (len) {
	var arr = [],
	str = "";
	for (var i = 1; i <= len; i++) {
		str = (i % 3) ? "" : "Fizz";
		str += (i % 5) ? "" : "Buzz";
		arr.push(str||i);
	}
	return arr;
};
var fizzBuzz = function () {
	console.log(getFizzBuzzStatements(100).join("\n"));
};
fizzBuzz();

Alternative: One liner



// One liner
for (i = 1; i <= 100; i++)
	console.log((((i % 3) ? "" : "Fizz") + (i % 5 ? "" : "Buzz")||i) + "\n")
// One liner
for (i = 1; i <= 100; i++)
	console.log((((i % 3) ? "" : "Fizz") + (i % 5 ? "" : "Buzz")||i) + "\n")

Alternative: Switches



var getFizzBuzzStatements = function (len) {
	var j,
	arr = [];
	for (var i = 1; i <= len; i++) {
		switch (i % 15) {
		case 0:
			arr.push("FizzBuzz");
			break;
		case 3:	case 6:	case 9:	case 12:
			arr.push("Fizz");
			break;
		case 5:	case 10:
			arr.push("Buzz");
			break;
		default:
			arr.push(i);
		}
	}
	return arr;
};
var fizzBuzz = function () {
	console.log(getFizzBuzzStatements(100).join("\n"));
};
var getFizzBuzzStatements = function (len) {
	var j,
	arr = [];
	for (var i = 1; i <= len; i++) {
		switch (i % 15) {
		case 0:
			arr.push("FizzBuzz");
			break;
		case 3:	case 6:	case 9:	case 12:
			arr.push("Fizz");
			break;
		case 5:	case 10:
			arr.push("Buzz");
			break;
		default:
			arr.push(i);
		}
	}
	return arr;
};
var fizzBuzz = function () {
	console.log(getFizzBuzzStatements(100).join("\n"));
};

Demo

Larry Battle

I love to program, and discover new tech. Check out my <a href="http://stackoverflow.com/users/527776/larry-battle">stackoverflow</a> and <a href="https://github.com/LarryBattle">github</a> accounts.

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Ratio.js – Fractions for javascript

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Hey Everyone,
I created a project called Ratio.js. Basically the goal of the project is to provide an simple object for dealing with fractions in javascript.
Check it out here and tell me what this.

Ratio.js

Sample Code



 
// converts decimal values into the form of a fraction.
a = Ratio.parse(1/2);
a.toString() == "1/2";
 
// converts strings in the form of "a/b" to a fraction a/b.
a = Ratio.parse( "1/2" );
a.toString() == "1/2";
 
var result = Ratio.parse( 12.12121212121212 ).reduce().toString();
result == "400/33";

// converts decimal values into the form of a fraction.
a = Ratio.parse(1/2);
a.toString() == "1/2";

// converts strings in the form of "a/b" to a fraction a/b.
a = Ratio.parse( "1/2" );
a.toString() == "1/2";

var result = Ratio.parse( 12.12121212121212 ).reduce().toString();
result == "400/33";

Simple Demo

Larry Battle

I love to program, and discover new tech. Check out my <a href="http://stackoverflow.com/users/527776/larry-battle">stackoverflow</a> and <a href="https://github.com/LarryBattle">github</a> accounts.

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Javascript Slides over Build Automation

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JavaScript + Jenkins = Winning!

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Eric Wendelin

Larry Battle

I love to program, and discover new tech. Check out my <a href="http://stackoverflow.com/users/527776/larry-battle">stackoverflow</a> and <a href="https://github.com/LarryBattle">github</a> accounts.

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