Get a part of html form external site

How can i get a part of the sorce code of a site for exampel if i would for say to ony want to get this part of code

<span class="definition">Anv&#228;nds n&#228;r man s&#228;ger hejd&#229; till n&#229;gon. Ha de G &#228;r samma sak som ha det bra, eller ha det g&#246;tt.</span><br /><br />

Form alot of code, and i want to do this in Javascript, and the code is comming from an external site, NAd this is node.js

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