what is the difference between chunk.write and chunk.render - dust.js

Question

I saw this,
chunk = chunk.write("<li>").render(bodies.block, context.push(items[i])).write("</li>\n");
Before seeing this code, i thought, render as something similar to flush, and write as something similar to "write in buffer", naturally leading to a code like below.
for loop
chunk.write("something")
end for loop
chunck.render();
But, as you can see in the first code, render is coming in between the writes. Can somebody explain the difference between these two functions.
#JAiro:
After reading your answer i tried the below code:
temaplate: You have {render} {write}
data:
{
"name": "Mick",
"render": function(c,ct,b){
chunk.render("Rendered {~n}");
},
write:function(c,ct,b){
chunk.write("Written {~n}")
}
}
Expected output:
you have Rendered
Written {~n}
Please note the {~n} after the word "Rendered" is interpreted but the {~n} after "Written" is not interpreted.
But the actual output is not same as the expected output.
Could you post a jsfiddle, that will help me in understanding.
The actual output is an empty string, which also indicate that there could be an error in the code.

Answer 1

The chunk.write method writes strings directly to the buffer.
On the other hand, chunk.render resolves variables contained in its argument and then writes the resulting string to the buffer.
You don't have to override the write and render function in the context.
Let me show you how it works.
Template
Hello {name}!, how are you?
Dust compiles the template to convert them in javascript. After compiling that template you are going to obtain something like:
return chk.write("Hello ").reference(ctx.get("name"), ctx, "h").write("! how are you?");
As you can see for "Hello" and "how are you?", dust uses chunk.write because it knows what it should print. However, dust doesn't know the value of {name} until it gets the context (JSON).
For that reason, it uses chunk.reference, because it will have to resolve the value of the variable name in the future. Dust is going to obtain the value of name from the JSON data.
You can read more about dust.js here:
http://linkedin.github.com/dustjs/wiki
And you can see working examples and try yours here:
http://linkedin.github.com/dustjs/test/test.html