jQuery Code and Syntax Guidelines for Improved Code Performance

If you want to publish your jQuery plugins following jQuery core code writing guidelines is a good idea. Here are some of the guidelines.

• Do NOT append an element to the DOM in your loop.

[code:js]// DO NOT DO THIS
for (var i=0; i<=rows.length; i++)
{
$(‘#myTable’).append(‘<tr><td>’+rows[i]+'</td></tr>’); }

// INSTEAD DO THIS
var tmp = ”;
for (var i=0; i<=rows.length; i++)
{
tmp += ‘<tr><td>’+rows[i]+'</td></tr>’;
}
$(‘#myTable’).append(tmp);[/code]

• Don’t use string concatenation, instead use array’s join() method for a very long strings.

[code:js]var tmp = [];
tmp[0] = ‘<tbody>’;
for (var i=1; i<=rows.length; i++)
{
tmp[i] = ‘<tr><td>’+rows[i-1]+'</td></tr>’;
}
tmp[tmp.length] = ‘</tbody>’;
$(‘#myTable’).append(tmp.join(”));[/code]

• Don’t use "string".match() for RegExp, instead use .test() or .exec()
• Local variables are declared and initialized on one line just below the function declaration with no extra line:

[code:js]function someFunction () {
var target = arguments[0] || {}, i = 1, name;

// Empty line and then the rest of the code
}[/code]

• All strings are in double quotes " ", not single quotes ‘ ‘:
• The last but not least, variable naming uses camelCase.

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