Avoid use of
== and != JS-0050
Anti-pattern
Minor
a month ago
—
a year old
Expected '!==' and instead saw '!='
1var clear="img/clear.gif" //path to clear.gif
2
3pngfix=function(){var els=document.getElementsByTagName('*');var ip=/\.png/i;var i=els.length;while(i-- >0){var el=els[i];var es=el.style;if(el.src&&el.src.match(ip)&&!es.filter){es.height=el.height;es.width=el.width;es.filter="progid:DXImageTransform.Microsoft.AlphaImageLoader(src='"+el.src+"',sizingMethod='crop')";el.src=clear;}else{var elb=el.currentStyle.backgroundImage;if(elb.match(ip)){var path=elb.split('"');var rep=(el.currentStyle.backgroundRepeat=='no-repeat')?'crop':'scale';es.filter="progid:DXImageTransform.Microsoft.AlphaImageLoader(src='"+path[1]+"',sizingMethod='"+rep+"')";es.height=el.clientHeight+'px';es.backgroundImage='none';var elkids=el.getElementsByTagName('*');if (elkids){var j=elkids.length;if(el.currentStyle.position!="absolute")es.position='static';while (j-- >0)if(!elkids[j].style.position)elkids[j].style.position="relative";}}}}}4window.attachEvent('onload',pngfix);
Expected '===' and instead saw '=='
1var clear="img/clear.gif" //path to clear.gif
2
3pngfix=function(){var els=document.getElementsByTagName('*');var ip=/\.png/i;var i=els.length;while(i-- >0){var el=els[i];var es=el.style;if(el.src&&el.src.match(ip)&&!es.filter){es.height=el.height;es.width=el.width;es.filter="progid:DXImageTransform.Microsoft.AlphaImageLoader(src='"+el.src+"',sizingMethod='crop')";el.src=clear;}else{var elb=el.currentStyle.backgroundImage;if(elb.match(ip)){var path=elb.split('"');var rep=(el.currentStyle.backgroundRepeat=='no-repeat')?'crop':'scale';es.filter="progid:DXImageTransform.Microsoft.AlphaImageLoader(src='"+path[1]+"',sizingMethod='"+rep+"')";es.height=el.clientHeight+'px';es.backgroundImage='none';var elkids=el.getElementsByTagName('*');if (elkids){var j=elkids.length;if(el.currentStyle.position!="absolute")es.position='static';while (j-- >0)if(!elkids[j].style.position)elkids[j].style.position="relative";}}}}}4window.attachEvent('onload',pngfix);
Expected '===' and instead saw '=='
213 document.onmousemove = '';
214 document.body.removeChild(tipid);
215 tipid.style.display = "none";
216 if (altText==false) a.setAttribute("title", sTitle);217 else a.setAttribute("alt", sTitle);
218 altText=false;
219}Expected '===' and instead saw '=='
59build = function (a, sTitle) {
60
61 if (a.title) a.title = "";
62 if (altText==true) a.alt = ""; 63
64 var tipContainer = document.createElement("div");
65 tipContainer.setAttribute("id", "unitip");Expected '===' and instead saw '=='
42 var a = element;
43 var id = a.getAttribute('id');
44
45 if (id != null && id.indexOf('recaptcha_') == 0) { 46 return;
47 }
48
Description
It is considered good practice to use the type-safe equality operators === and !== instead of their regular counterparts == and !=.
The strict equality operators (=== and !==) use the strict equality comparison algorithm to compare two operands.
- If the operands are of different types, return
false. - If both operands are objects, return
trueonly if they refer to the same object. - If both operands are
nullor both operands areundefined, returntrue. - If either operand is
NaN, returnfalse. - Otherwise, compare the two operand's values:
- Numbers must have the same numeric values.
+0and-0are considered to be the same value. - Strings must have the same characters in the same order.
- Booleans must be both
trueor bothfalse.
- Numbers must have the same numeric values.
The most notable difference between this operator and the equality (==) operator is that if the operands are of different types, the == operator attempts to convert them to the same type before comparing.
Bad Practice
a == b
foo == true
bananas != 1
value == undefined
typeof foo == 'undefined'
'hello' != 'world'
0 == 0
true == true
foo == null
Recommended
a === b
foo === true
bananas !== 1
value === undefined
typeof foo === 'undefined'
'hello' !== 'world'
0 === 0
true === true
foo === null