Vâng, đúng như tiêu đề của bài viết đã nói, 10 thủ thuật lập trình này vô cùng nhỏ gọn và đơn giản để sử dụng nhưng hiếm khi chúng ta nhớ. Vì vậy tác giả liệt kê giúp bạn các thủ thuật để tối ưu và đơn giản hóa các công việc cần phải thực hiện khi lập trình với ngôn ngữ JavaScript.

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As I have previously stated in prior posts, JavaScript is the one of the most utilized programming languages, because a large majority of the browsers are compatible with it and make use of it. JavaScript has become very accepted, very quickly, because it is so straightforward and has a wide-range of capabilities. Many programmers used to think that JavaScript was a toy language, but the emergence of AJAX into the market manifested something completely to the contrary, because it showed JavaScript diverse capabilities and functions. Since this discovery, programmers can create web applications that give the impression of a desk top application, which is helpful because data can be changed more quickly. Here are some mini-tips and tricks to help beginners better use JavaScript. JavaScript is very wide and has so many styles, so it can get very tricky. Moreover, it has so many ways of programming, but I picked 10 tips that I think are a good starting place for beginners to understand JavaScript. If you see these scripts somewhere, here are some tips to help you through them. This is not even the tip of the iceberg with JavaScript capabilities, but it is a start! Please feel free to leave your comments, questions, extra tips, or concerns, but remember this is a post for beginners!! I love to hear from fellow developers! Enjoy!

Add an Element at the End of an Array

This tip allows you to add an element at the end of an array using the length property, because the length property is going to be one number higher than the position of the last element in the array. This way acts the same as "push" method. For example:

var myArray = [];
myArray[myArray.length] = 'New Element';

Resize the Length of an Array

The length property is a not read only, because you can set values to it. Moreover, you can use it to increase or decrease the size of the array. For example:

var myArray = [1,2,3];
myArray.length // 3
myArray.length = 2; //Delete the last element
myArray.length = 20 // add 18 elements to the array; the elements have the undefined value.

Convert any Data Type to Boolean Using "!!"

This technique allows you to convert any data type, like string, number, or integer, to a Boolean using the "!!". For example:

var myString = '23255';
typeof myString; //String

myString = !!myString;
typeof myString  //Boolean

Convert from Number to String

This tip permits you to convert from number to string by adding an empty string at the end of the number. Example:

var mynumber = 234;
typeof mynumber; //Number

mynumber += '';
typeof mynumber; //String

Know How Many Variables are Expected by a Function

This is a great tip that allows you to know exactly how many variables are expected by a function. For example:

function add_nums(num1, num2){
    return num1 + num2;
}
add_nums.length // 2 is the amount of parameters expected by the function add_nums

Know How Many Parameters are Received by the Function Using "arguments" Object

This technique lets you know how many parameters are received by the function using "arguments" object. For example:

function add_nums(){
    return arguments.length;
}

add_nums(23,11,32,56,89,89,89,44,6); //this return the number 9

This is very useful at the time you need to check the number of parameter in validations or even to create a function with undetermined parameters.

function sum_three_nums( ){
 if(arguments.length!=3) throw new Error('received ' + arguments.length + ' parameters and should work with 3');

}

sum_three_nums(23,43); //Return the error message

function sum_num(){
  var total = 0;
  for(var i=0;i<arguments.length;i++){
    total+=arguments[i];
  }
  return total;
}

sum_num(2,34,45,56,56);

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bởi shyam raj, 03/06/2010 10:06 PM
8 Amazing JavaScript Image Zoom Scripts Phản hồi

Iam shyam raj editor of yestutor.blogspot.com. You can add my post on your site. Just add my site source to your post.

bởi buy term paper, 09/06/2010 06:06 PM
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well, the theme is gorgeous, thanks for sharing it with us

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