1. Set node's checkbox / radio to disabled. It is valid when [setting.check.enable = true]
2. zTree support identification string 'true' & 'false'.
3. Please don't change this attribute of the nodes which have been created. If you want to disable or undisable the nodes, please use 'setChkDisabled()' methods.
4. When zTree initialize the nodes, if you need to the child nodes automatically inherit the 'chkDisabled' attribute, please see 'setting.check.chkDisabledInherit'.
Default: false
true means: this node's checkbox / radio is disabled.
false means: this node's checkbox / radio is able.
var nodes = [
{ "id":1, "name":"test1", "checked":true, "chkDisabled":true},
{ "id":2, "name":"test2", "chkDisabled":true},
{ "id":3, "name":"test3"}
]