onblur (HTML attribute)

Browser support (more…)
IE5.5+ FF1+ SA1.3+ OP9.2+
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As with many of the other event attributes, this is the counterpart of another attribute: onblur is the opposite of the onfocus attribute. It captures the moment that an element loses focus either because the user has used the tab key to move to the next element on the page, or has placed the cursor in another section of the page.

onblur is most often used with form validation code. When the user leaves a form field, the onblur attribute is used to call a piece of script that performs some sort of validation on the field to make sure that the correct data was entered, rather than leaving all the validation to execute at the form’s end.


In this example, the onblur event calls a function called validate:

<input type="text" title="Date format = DD/MM/YYYY"
    onfocus="revealTitleHelp();" onblur="validate(this.value);"


This attribute has no fixed value. It’s up to the author to decide on the scripting that’s included here, be that a call to one or more defined functions, or a simple alert() statement.


Internet Explorer Firefox Safari Opera
5.5 6.0 7.0 1.0 1.5 2.0 1.3 2.0 3.0 9.2 9.5
Full Full Full Full Full Full Full Full Full Full Full

Every browser listed supports this attribute. However, inline event handlers such as this should be avoided. In the same way that inline CSS styles are frowned upon but externally defined CSS styles are considered good practice, inline event handlers should be stripped out and replaced with events attached unobtrusively through the DOM.

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