Kata

This time we learn about two useful methods of Number objects: toString() and toLocaleString(). the basic usage of the two methods is to convert a number into a string. look at this:

var num=111;
var a=num.toString(), 
    b=num.toLocaleString(), 
    c=num+""
console.log([a,b,c])   //put them to an array, we can see the quotes
//output: [ '111', '111', '111' ]

We can see, if you just want to translate a number into a string representation, in the general case the results obtained in these ways is the same. I love to use the last one, cause I'm lazy ;-)

But these two methods have other uses as well.

When used toLocaleString() converted a number to a string. the results obtained are in the order of the local numeric format(I don't have this experience. it is always the same as toString() in my here).

And toString() of Number object has a more special usage: According to the base output different strings.

NumberObject.toString(radix)

radix is optional parameter. if ignored it, the output will be the default decimal. If not, like this:

var num=111;
var a=num.toString(2), 
    b=num.toString(8), 
    c=num.toString(16), 
console.log([a,b,c])
//output: [ '1101111', '157', '6f' ]

They are converted to binary, octal and hexadecimal.

Ok, lesson is over. let's us do some task with Number .toString().

Task

Coding in function colorOf. function accept 3 parameter:r g b. It means value of color red green and blue. the value range is 0-255.

Use toString(16) Convert numbers r g b to hex string form. at last, combine them to a web color code and return it.

the color code should starting with "#". and then use 2 characters per color.

for example:

colorOf(255,0,0) should return "#ff0000"
colorOf(0,111,0) should return "#006f00"
colorOf(1, 2 ,3) should return "#010203"

That's all of your work. My work is print your color code on your screen.

Series

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• #1: create your first JS function helloWorld
• #2: Basic data types--Number
• #3: Basic data types--String
• #4: Basic data types--Array
• #5: Basic data types--Object
• #6: Basic data types--Boolean and conditional statements if..else
• #7: if..else and ternary operator
• #8: Conditional statement--switch
• #9: loop statement --while and do..while
• #10: loop statement --for
• #11: loop statement --break,continue
• #12: loop statement --for..in and for..of
• #13: Number object and its properties
• #14: Methods of Number object--toString() and toLocaleString()
• #15: Methods of Number object--toFixed(), toExponential() and toPrecision()
• #16: Methods of String object--slice(), substring() and substr()
• #17: Methods of String object--indexOf(), lastIndexOf() and search()
• #18: Methods of String object--concat() split() and its good friend join()
• #19: Methods of String object--toUpperCase() toLowerCase() and replace()
• #20: Methods of String object--charAt() charCodeAt() and fromCharCode()
• #21: Methods of String object--trim() and the string template
• #22: Unlock new skills--Arrow function,spread operator and deconstruction
• #23: methods of arrayObject---push(), pop(), shift() and unshift()
• #24: methods of arrayObject---splice() and slice()
• #25: methods of arrayObject---reverse() and sort()
• #26: methods of arrayObject---map()
• #27: methods of arrayObject---filter()
• #28: methods of arrayObject---every() and some()
• #29: methods of arrayObject---concat() and join()
• #30: methods of arrayObject---reduce() and reduceRight()
• #31: methods of arrayObject---isArray() indexOf() and toString()
• #32: methods of Math---round() ceil() and floor()
• #33: methods of Math---max() min() and abs()
• #34: methods of Math---pow() sqrt() and cbrt()
• #35: methods of Math---log() and its family
• #36: methods of Math---kata author's lover:random()
• #37: Unlock new weapon---RegExp Object
• #38: Regular Expression--"^","$", "." and test()
• #39: Regular Expression--"?", "*", "+" and "{}"
• #40: Regular Expression--"|", "[]" and "()"
• #41: Regular Expression--""
• #42: Regular Expression--(?:), (?=) and (?!)