jQuery.fn.empty()和jQuery.fn.html('')有什么区别? [英] What's the difference between jQuery.fn.empty() and jQuery.fn.html('')?

问题描述

两者之间是否有任何区别

Is there any difference between

$("#header").empty()

和

$("#header").html('')

?

我还应该使用哪个? $("#header").empty()更具可读性，但有什么东西会比$("#header").html('')更快?

Also, which should I use? $("#header").empty() is more readable, but how could anything be faster than $("#header").html('')?

推荐答案

两者之间没有功能上的区别.使用.empty()，因为它更短(更简洁)并且更易读.

There is no functional difference between the two. Use .empty() since it is shorter (more terse) and more readable.

不用担心性能差异.请记住，没有使用jQuery是因为它的运行时间比原始JavaScript快.之所以使用它，是因为它更快地编写.开发人员时间所花的时间远远超过处理器时间.

Don't worry about the performance difference. Remember, jQuery isn't used because it runs faster than vanilla JavaScript — it's used because it's written faster. Developer time is worth far more than processor time.

已经有一个jsPerf可以比较相对性能: http://jsperf.com/jquery- empty-vs-html . 每个测试案例都显示.empty()更快.

There's already a jsPerf to compare the relative performance: http://jsperf.com/jquery-empty-vs-html. Every single test case shows that .empty() is faster.

直接来自jQuery来源:

Straight from the jQuery source:

empty: function() {
    for ( var i = 0, elem; (elem = this[i]) != null; i++ ) {
        // Remove element nodes and prevent memory leaks
        if ( elem.nodeType === 1 ) {
            jQuery.cleanData( elem.getElementsByTagName("*") );
        }

        // Remove any remaining nodes
        while ( elem.firstChild ) {
            elem.removeChild( elem.firstChild );
        }
    }

    return this;
},

html: function( value ) {
    if ( value === undefined ) {
        return this[0] && this[0].nodeType === 1 ?
            this[0].innerHTML.replace(rinlinejQuery, "") :
            null;

    // See if we can take a shortcut and just use innerHTML
    } else if ( typeof value === "string" && !rnocache.test( value ) &&
        (jQuery.support.leadingWhitespace || !rleadingWhitespace.test( value )) &&
        !wrapMap[ (rtagName.exec( value ) || ["", ""])[1].toLowerCase() ] ) {

        value = value.replace(rxhtmlTag, "<$1></$2>");

        try {
            for ( var i = 0, l = this.length; i < l; i++ ) {
                // Remove element nodes and prevent memory leaks
                if ( this[i].nodeType === 1 ) {
                    jQuery.cleanData( this[i].getElementsByTagName("*") );
                    this[i].innerHTML = value;
                }
            }

        // If using innerHTML throws an exception, use the fallback method
        } catch(e) {
            this.empty().append( value );
        }

    } else if ( jQuery.isFunction( value ) ) {
        this.each(function(i){
            var self = jQuery( this );

            self.html( value.call(this, i, self.html()) );
        });

    } else {
        this.empty().append( value );
    }

    return this;
},

.empty()不必检查各种可能的参数类型；可以直接删除DOM元素.

.empty() doesn't have to deal with checking the different possible argument types; it can get right down to chucking out DOM elements.

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