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DXM Developer Knowledge Base

document.write

document.write (DW): 

  • Executes where encountered by User 

  • Can be used for adding script elements 

  • Only works while the page is loading; If you call it after the page is done loading, it will overwrite the whole page. 

 

Why It Is Used: 

  • You can overwrite the entire content in a frame/iframe 

  • Way to embed inline content from an external script (to host/domain)  

  • It is the most reliable way for the content (Widget or Ad) to “know” where the HTML author intends for it to be placed. 

  • Scripts can have a negative impact on page performance and modern browsers have taken to blocking scripts. DW can be used to inject and bypass these blocks. 

  • It works everywhere, all the time 

 

Why It Shouldn’t Be Used: 

  • Serializes the rendering engine to pause until external script is loaded. This could take much longer to load than an internal (none-DW) script. 

  • Browser must download, parse, and execute the first external JavaScript resource before it executes the document.write() that fetches the additional external resources.  

  • No single script should have the right to control (alter) a page before it’s ready to be viewed  

 

Common Examples: 

  • Twitter Stream 

  • Google Analytics 

 

What We Could Do To Improve User Experience with Tag Auditor: 

  • Look for DW in the code 

  • Make a note in the Db (Flag) 

  • When a Tag is seen firing from a Tag Manager AND placed directly on the site 

  • Cross reference the flag 

  • Display a option to show with/without DW Relationship(s) 

  • Like New Tag & Non-Secure Filters 
     

 

What Authors Can Do To Minimize The Use of document.write 

  • Use safer embedding tools like: