zoukankan      html  css  js  c++  java
  • The "with" keyword in Javascript

    The "with" keyword is used to specify an object to which all of the unreferenced properties and methods in a following block of code are to be applied.

    for example:

    Instead of coding

    var x = document.body.scrollLeft;
    document.write('text1');
    document.write('text2');
    document.write('text3');

    you could use

    with document {
    var x = body.scrollLeft;
    write('text1');
    write('text2');
    write('text3');
    }

    Of course using this construct results in code that may be somewhat shorter but it will also take a lot longer to run since each variable within the with block needs to be checked to see whether or not it is a property of the object that the with block references.

    A more efficient coding that is almost as short is where you assign a much shorter name to reference the object and use that instead of the original object name. For example:

    var d = document;
    var x = d.body.scrollLeft;
    d.write('text1');
    d.write('text2');
    d.write('text3');
    No replies - reply
     

  • 相关阅读:
    windows nginx
    stdClass 标准
    array_merge
    array_pop
    array_push
    array_unique
    GMT与UTC简介(转)
    curl-手册
    13.5. zipfile — Work with ZIP archives
    7. Input and Output
  • 原文地址:https://www.cnblogs.com/jinweijie/p/566610.html
Copyright © 2011-2022 走看看