change background with js

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2document.body.style.backgroundColor = "red"; 

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2 document.body.style.backgroundPosition = "top right"; 

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2 object.style.background
3 

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2 document.body.style.background; 

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2 object.style.background = "color image
3repeat attachment position size origin clip|initial|inherit"
4 

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2document.getElementById("myDIV").style.background = "url('smiley.gif') blue repeat-x center"; 

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2document.body.style.backgroundAttachment = "fixed"; 

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2document.body.style.backgroundRepeat = "repeat-y";