javascript語言精粹-筆記

walkDOM

function walkTheDOM(node, func) {
    func(node); 
    node = node.firstChild; 
    while (node) { 
        walkTheDOM(node, func); 
        node = node.nextSibling; 
    } 
} 

getElementsByClassName

function getElementsByClassName(className) { 
    var results = []; 
    walkTheDOM(document.body, function (node) { 
        var a, c = node.className, i; 
        if (c) { 
            a = c.split(' '); 
            for (i = 0; i < a.length; i += 1) { 
                if (a[i] === className) { 
                    results.push(node); 
                    break; 
                } 
            } 
        } 
    }); 
    return results; 
} 

第六章

6.5 判斷是不是數組

var is array = function (value) {
    return value &&
    typeof value.splice === 'function' &&
    typeof value.length=== 'number' &&
    typeof value === 'object' &&
    ! (value.propertyIsEnumerable ('length'));
};

寫一個Reduce

Array. method ('reduce', function(f,value) {
var i;
for （i=0;i<this.length; i +=1) {
  value = f(this [i], value);
}
return value;
})

第七章 正則表達式

7.1 匹配url的正則

var parse_url =/^ (?: ([A-Za-z]+) :)? (\/{0,3}) ( [0-9.\-A-Za-z]+)(?:: (d+))? (?:\/([^?#]*))?(?:\? ([^#]*))? (?:#(.*))?$/;

var url ="http://www.ora.com: 80/goodparts?q#fragment";

匹配數字的reg

var parse_number =/^-?\d+(?:\.\d*)? (?:e [+\-]?\dt)?S/i;

var test= function (num) {
document.writeln(parse number.test (num) );

};

true test ("1");
false test ('number');
true  test('98.6");
false  test ('132.21.86.100');
true  test ('123.45E-67');
false  test ('123.45D-67');