javascript语言精粹-笔记

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 判断是不是数组

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

写一个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 正则表达式

7.1 匹配url的正则

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

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

匹配数字的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');