I'm using the excellent UltiSnips Vim plugin to help improve my development workflow. I've been using it for several years now, and it has really helped me automate a lot of my redundant typing while coding.
Anyhow: I'm attempting to define a snippet that helps me generate Javascript require statements.
A normal Javascript require statement looks something like this:
let express = require('express');
So, here's the snippet I defined:
snippet req "require a module" b
let ${1} = require('${2}');
endsnippet
This lets me type req in Vim, which will then move my cursor to the ${1} position in the snippet so I can define the variable name. Once I hit a second time, my cursor will be moved to the location of ${2} in the snippet, this way I can define the actual Javascript module name to import.
This works fine, but what I'd like to do is take it one step further. I'd like to make a snippet such that:
When I enter a value for ${1}, the value ${2} is updated to be the value of ${1} by default. This way, I can save on typing the same module name twice in certain situations.
The idea is that I should be able to do something like this:
snippet req "require a module" b
let ${1} = require('${2:${1}}');
endsnippet
This way, if I type:
req<tab>express
I should end up with the following expanded line:
let express = require('express');
However, it should also work in this situation:
req<tab>exp<tab>express
Which would output:
let exp = require('express');
Does that make sense?
Anyhow: any help would be appreciated! The code sample above does not work like I thought it would. The ${2:${1}} bit is ignored and doesn't work as expected (it doesn't set the placeholder value of ${2} to ${1}).
The following snippet satisfy both req<tab>express and req<tab>exp<tab>express: (a slight modification of your idea)
snippet req "require a module" b
let ${1} = require('${0:$1}');
endsnippet
$1 is mirror for placeholder ${1}. Also replaced 2 with 0 as snippet ends in this placeholder.
To add visual support just add ${VISUAL} to placeholders. As @lwassink provided instructions, i just give snippet:
snippet req "require a module" b
let ${1:${VISUAL}} = require('${0:$1}');
endsnippet