Add conceal to double and tripple equal

* Add changes to `README.md`

Author: cabaalexander

README.md

@@ -68,18 +68,20 @@ Please note this can have a dramatic effect on performance.
 You can customize concealing characters, if your font provides the glyph you want, by defining one or more of the following
 variables:
 
-    let g:javascript_conceal_function             = "ƒ"
-    let g:javascript_conceal_null                 = "ø"
-    let g:javascript_conceal_this                 = "@"
-    let g:javascript_conceal_return               = "⇚"
-    let g:javascript_conceal_undefined            = "¿"
-    let g:javascript_conceal_NaN                  = "ℕ"
-    let g:javascript_conceal_prototype            = "¶"
-    let g:javascript_conceal_static               = "•"
-    let g:javascript_conceal_super                = "Ω"
-    let g:javascript_conceal_arrow_function       = "⇒"
-    let g:javascript_conceal_noarg_arrow_function = "🞅"
+    let g:javascript_conceal_function                  = "ƒ"
+    let g:javascript_conceal_null                      = "ø"
+    let g:javascript_conceal_this                      = "@"
+    let g:javascript_conceal_return                    = "⇚"
+    let g:javascript_conceal_undefined                 = "¿"
+    let g:javascript_conceal_NaN                       = "ℕ"
+    let g:javascript_conceal_prototype                 = "¶"
+    let g:javascript_conceal_static                    = "•"
+    let g:javascript_conceal_super                     = "Ω"
+    let g:javascript_conceal_arrow_function            = "⇒"
+    let g:javascript_conceal_noarg_arrow_function      = "🞅"
     let g:javascript_conceal_underscore_arrow_function = "🞅"
+    let g:javascript_conceal_double_equal              = "≈"
+    let g:javascript_conceal_triple_equal              = "≡"
 
 
 You can enable concealing within VIM with:

syntax/javascript.vim

@@ -174,6 +174,8 @@ exe 'syntax match jsFunction /\<function\>/      skipwhite skipempty nextgroup=j
 exe 'syntax match jsArrowFunction /=>/           skipwhite skipempty nextgroup=jsFuncBlock,jsCommentFunction '.(exists('g:javascript_conceal_arrow_function') ? 'conceal cchar='.g:javascript_conceal_arrow_function : '')
 exe 'syntax match jsArrowFunction /()\ze\s*=>/   skipwhite skipempty nextgroup=jsArrowFunction '.(exists('g:javascript_conceal_noarg_arrow_function') ? 'conceal cchar='.g:javascript_conceal_noarg_arrow_function : '')
 exe 'syntax match jsArrowFunction /_\ze\s*=>/    skipwhite skipempty nextgroup=jsArrowFunction '.(exists('g:javascript_conceal_underscore_arrow_function') ? 'conceal cchar='.g:javascript_conceal_underscore_arrow_function : '')
+exe 'syntax match jsDoubleEqual   /=\{2}/        contained '.(exists('g:javascript_conceal_double_equal') ? 'conceal cchar='.g:javascript_conceal_double_equal : '')
+exe 'syntax match jsTripleEqual   /=\{3}/        contained '.(exists('g:javascript_conceal_triple_equal') ? 'conceal cchar='.g:javascript_conceal_triple_equal : '')
 
 " Classes
 syntax keyword jsClassKeyword           contained class
@@ -231,7 +233,7 @@ if exists("javascript_plugin_flow")
 endif
 
 syntax cluster jsExpression  contains=jsBracket,jsParen,jsObject,jsTernaryIf,jsTaggedTemplate,jsTemplateString,jsString,jsRegexpString,jsNumber,jsFloat,jsOperator,jsOperatorKeyword,jsBooleanTrue,jsBooleanFalse,jsNull,jsFunction,jsArrowFunction,jsGlobalObjects,jsExceptions,jsFutureKeys,jsDomErrNo,jsDomNodeConsts,jsHtmlEvents,jsFuncCall,jsUndefined,jsNan,jsPrototype,jsBuiltins,jsNoise,jsClassDefinition,jsArrowFunction,jsArrowFuncArgs,jsParensError,jsComment,jsArguments,jsThis,jsSuper,jsDo,jsForAwait,jsAsyncKeyword,jsStatement,jsDot
-syntax cluster jsAll         contains=@jsExpression,jsStorageClass,jsConditional,jsRepeat,jsReturn,jsException,jsTry,jsNoise,jsBlockLabel
+syntax cluster jsAll         contains=@jsExpression,jsStorageClass,jsConditional,jsRepeat,jsReturn,jsException,jsTry,jsNoise,jsBlockLabel,jsDoubleEqual,jsTripleEqual
 
 " Define the default highlighting.
 " For version 5.7 and earlier: only when not done already