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<title>example</title>
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pre{
border: thin solid black;
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<pre id="results"></pre>
<img id="caomei"src="img/4d0df8064383e78d74e07014e7ccd0ee.jpg" name="image" alt="caomei">
<p id="tblock">
There are lots of different kinds of fruit.There are over 500 varieties of <span id="banana">banana</span> alone.By the time we add the countless types of apples,oranges,and other well-known fruit,we are faced with thousands of choices.
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<img id="apple" src="img/63fddd61e1afe42e38c6ce76910be815.jpg" name="image" alt="apple">
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One of the most interesting aspects of fruit is the variety available in each country.I live near London,in an area which is known for its apples.
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<img id="san" src="img/161026fa577b8f3aa88187bd67b546fd.jpg" alt="san" />
<script>
var resultsElement=document.getElementById("results");
var elems=document.getElementById("tblock").getElementsByTagName("span");
resultsElement.innerHTML+="there are "+elems.length+" span elements(getelement方法)\n";
var elems2=document.getElementById("tblock").querySelectorAll("span");
resultsElement.innerHTML+="there are "+elems2.length+" span elements(getelement+css方法)\n";
var elems3=document.querySelectorAll("#tblock>span");
resultsElement.innerHTML+="there are "+elems3.length+" span elements(css選擇器方法)\n";
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resultsElement.innerHTML+="there are "+elems3.length+" span elements(css選擇器方法)\n";這句裡面，=前面怎麼會有+號？
+=表示保留之前的內容，並且把後面的附加上去。
光是+，之間的文字就沒有了。
