feat(filters): add squish filter (#943)

docs/source/_data/sidebar.yml

@@ -94,6 +94,7 @@ filters:
   sort: sort.html
   sort_natural: sort_natural.html
   split: split.html
+  squish: squish.html
   strip: strip.html
   strip_html: strip_html.html
   strip_newlines: strip_newlines.html

docs/source/filters/squish.md

@@ -0,0 +1,18 @@
+---
+title: squish
+---
+
+{% since %}v10.28.0{% endsince %}
+
+Removes leading and trailing whitespace from a string, and replaces every run of whitespace inside it with a single space.
+
+Input
+```liquid
+{{ "  Hello   there,
+    Major Tom.  " | squish }}
+```
+
+Output
+```text
+Hello there, Major Tom.
+```

src/filters/string.ts

@@ -128,6 +128,12 @@ export function strip_newlines (this: FilterImpl, v: string) {
   return str.replace(/\r?\n/gm, '')
 }
 
+export function squish (this: FilterImpl, v: string) {
+  const str = stringify(v)
+  this.context.memoryLimit.use(str.length)
+  return str.replace(/\s+/g, ' ').trim()
+}
+
 export function capitalize (this: FilterImpl, str: string) {
   str = stringify(str)
   this.context.memoryLimit.use(str.length)

test/integration/filters/string.spec.ts

@@ -153,6 +153,26 @@ describe('filters/string', function () {
             '{{ string_with_newlines | strip_newlines }}',
     'Hellothere')
   })
+  describe('squish', function () {
+    it('should collapse whitespace between words', function () {
+      return test('{{ "Hello   World!" | squish }}', 'Hello World!')
+    })
+    it('should strip leading and trailing whitespace', function () {
+      return test('{{ "  HelloWorld!  " | squish }}', 'HelloWorld!')
+    })
+    it('should treat newlines and tabs as whitespace', function () {
+      return test('{{ " \n\t\r\nHello  \n\t World!  \n" | squish }}', 'Hello World!')
+    })
+    it('should return empty string for whitespace only', function () {
+      return test('{{ " \n\t " | squish }}', '')
+    })
+    it('should stringify a number', function () {
+      return test('{{ 5 | squish }}', '5')
+    })
+    it('should return empty string for undefined', function () {
+      return test('{{ nosuchthing | squish }}', '')
+    })
+  })
   describe('truncate', function () {
     it('should truncate when string too long', function () {
       return test('{{ "Ground control to Major Tom." | truncate: 20 }}',