Convert a string to camelCase (string exercise)

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    <span style="background-color: #f5f5f5; color: #008000;">//</span><span style="background-color: #f5f5f5; color: #008000;"> //将字符串转变为驼峰样式</span>
    <span style="background-color: #f5f5f5; color: #008000;">//</span><span style="background-color: #f5f5f5; color: #008000;">     var srt1="the_sec_container";</span>
    <span style="background-color: #f5f5f5; color: #008000;">//</span><span style="background-color: #f5f5f5; color: #008000;">     var arr= srt1.split('_');</span>
    <span style="background-color: #f5f5f5; color: #008000;">//</span><span style="background-color: #f5f5f5; color: #008000;">     // document.write(arr);</span>
    <span style="background-color: #f5f5f5; color: #008000;">//</span><span style="background-color: #f5f5f5; color: #008000;">     for (var i = 0; i < arr.length; i++) {</span>
    <span style="background-color: #f5f5f5; color: #008000;">//</span><span style="background-color: #f5f5f5; color: #008000;">         arr[i]=arr[i].charAt(0).toLocaleUpperCase()+arr[i].substring(1);</span>
    <span style="background-color: #f5f5f5; color: #008000;">//</span><span style="background-color: #f5f5f5; color: #008000;">     }</span>
    <span style="background-color: #f5f5f5; color: #008000;">//</span><span style="background-color: #f5f5f5; color: #008000;">     document.write(arr.join(''));</span>
    <span style="background-color: #f5f5f5; color: #008000;">//</span><span style="background-color: #f5f5f5; color: #008000;">     返回只带数字的字符串</span>
        <span style="background-color: #f5f5f5; color: #0000ff;">var</span><span style="background-color: #f5f5f5; color: #000000;"> st1 </span><span style="background-color: #f5f5f5; color: #000000;">=</span> <span style="background-color: #f5f5f5; color: #000000;">'</span><span style="background-color: #f5f5f5; color: #000000;">hgo3476H5course75</span><span style="background-color: #f5f5f5; color: #000000;">'</span><span style="background-color: #f5f5f5; color: #000000;">;
        </span><span style="background-color: #f5f5f5; color: #0000ff;">var</span><span style="background-color: #f5f5f5; color: #000000;"> st2 </span><span style="background-color: #f5f5f5; color: #000000;">=</span><span style="background-color: #f5f5f5; color: #000000;"> st1.substring(</span><span style="background-color: #f5f5f5; color: #000000;">3</span><span style="background-color: #f5f5f5; color: #000000;">,</span><span style="background-color: #f5f5f5; color: #000000;">7</span><span style="background-color: #f5f5f5; color: #000000;">)</span><span style="background-color: #f5f5f5; color: #000000;">+</span><span style="background-color: #f5f5f5; color: #000000;">st1.substring(</span><span style="background-color: #f5f5f5; color: #000000;">8</span><span style="background-color: #f5f5f5; color: #000000;">,</span><span style="background-color: #f5f5f5; color: #000000;">9</span><span style="background-color: #f5f5f5; color: #000000;">)</span><span style="background-color: #f5f5f5; color: #000000;">+</span><span style="background-color: #f5f5f5; color: #000000;">st1.substring(</span><span style="background-color: #f5f5f5; color: #000000;">15</span><span style="background-color: #f5f5f5; color: #000000;">,</span><span style="background-color: #f5f5f5; color: #000000;">17</span><span style="background-color: #f5f5f5; color: #000000;">);</span><span style="background-color: #f5f5f5; color: #008000;">//</span><span style="background-color: #f5f5f5; color: #008000;">后面写的数字不包括</span>
<span style="background-color: #f5f5f5; color: #000000;">        document.write(st2);

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Some simple string operations, everyone is welcome to refer to and learn.