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Commit3c82ebb

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Deprecated: improve .trim for strings containing lots of whitespaces
The old implementation took O(N^2) time to trim the string when multipleadjacent spaces were present.For instance, consider the string "A B" (10 spaces between A and B).Then old regexp /[\s]+$/ would take 10 steps until it realizesthe regexp does not match at position 1.Then it would try to match the regexp at position 2, and it would take 9 steps.Then 8 steps for position 3, ... so it would take 10*10/2 steps untilit figures out the regexp does not match.The new approach is to require "non-whitespace" char before the whitespace run,so it spends just one step for each space in the string.
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‎src/deprecated.js

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Original file line numberDiff line numberDiff line change
@@ -15,7 +15,13 @@ define( [
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// Support: Android <=4.0 only
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// Make sure we trim BOM and NBSP
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varrtrim=/^[\s\uFEFF\xA0]+|[\s\uFEFF\xA0]+$/g;
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// Require that the "whitespace run" starts from a non-whitespace
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// to avoid O(N^2) behavior when the engine would try matching "\s$" at each space position.
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// It is important that non-whitespace char is mandatory for regexp performance reasons,
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// however, it does not break correctness since whitespace-only string will be trimmed by ltrim above.
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varltrim=/^[\s\uFEFF\xA0]+/,
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rtrim=/([^\s\uFEFF\xA0])[\s\uFEFF\xA0]+$/,
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useDefaultTrim=false;
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// Bind a function to a context, optionally partially applying any
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// arguments.
@@ -79,9 +85,16 @@ jQuery.isNumeric = function( obj ) {
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!isNaN(obj-parseFloat(obj));
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};
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if(String.prototype.trim){
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useDefaultTrim="_"===" \uFEFF\xA0_\uFEFF\xA0 ".trim();
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}
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jQuery.trim=function(text){
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returntext==null ?
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"" :
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(text+"").replace(rtrim,"");
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if(text==null){
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return"";
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}
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returnuseDefaultTrim ?
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(text+"").trim() :
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(text+"").replace(ltrim,"").replace(rtrim,"$1");
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};
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});

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