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如何包含JavaScript庫?

[英]How to include JavaScript libraries?

我在代碼中包含proj4.js JavaScript庫時遇到了麻煩。 代碼如下所示:

<!DOCTYPE html>
<html>
<head>
    <title>Proj4js Testing</title>
</head>
<body onload="convertCoordinates()">
    <script type="text/javascript" src="proj4.js">
        function convertCoordinates() {
            var sourceProjection = "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs";
            var targetProjection = "+proj=utm +zone=33 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs";
            proj4(sourceProjection, targetProjection, [15, 55]);
            alert("Done!");
        }
    </script>
</body>
</html>

但它永遠不會給我一條消息說“完成!”。 我對JavaScript知之甚少,但我在這段代碼中看不到問題。 我按照GitHub上的用戶指南進行操作

它們需要是單獨的<script>標記:

<script type="text/javascript" src="proj4.js"></script>
<script type="text/javascript" >
    function convertCoordinates() {
        var sourceProjection = "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs";
        var targetProjection = "+proj=utm +zone=33 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs";
        proj4(sourceProjection, targetProjection, [15, 55]);
        alert("Done!");
    }
</script>

您無法將內聯JavaScript代碼與外部加載的腳本結合使用。 相反,只需將腳本拆分為兩個單獨的塊:

<script type="text/javascript" src="proj4.js"></script>

<script type="text/javascript">
        function convertCoordinates() {
            var sourceProjection = "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs";
            var targetProjection = "+proj=utm +zone=33 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs";
            proj4(sourceProjection, targetProjection, [15, 55]);
            alert("Done!");
        }
</script>

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