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    javascript当中null和undefined的==和===的比较

    例 3.1.3(null和undefined的==和===的比较) <head> <meta http-equiv="content-type" content="text/html; charset=utf-8"/> </head> <script> //马克-to-win:声明变量x /* if a value is not set, its typeof is undefined, its value is undefined, if a value= null, its typeof is object, its value is null,but when you use == to test, they are the same, but when to use === to test, they are not the same,== means as long as value is the same, ok, but === means type also must be equal. */ var x; var z1 = "d"; var y = null; // document.writeln("z1 is"+z1); /*if you cancel commenting out the following statement, it will give the blank page, which means it has error.*/ // document.writeln(zyx); document.writeln(x + " is x"); document.writeln(typeof(x) + " is typeof(x)"); document.writeln(y + " is y"); document.writeln(typeof(y) + " is typeof(y)"); var z = undefined; document.writeln(z + " is z"); document.writeln(typeof(z) + " is typeof(z)"); if (y == undefined) { document.writeln('null and undefined is interchangable'); } if (z1 != null) { document.writeln('z1 != null'); } if (y === undefined) { document.writeln('null and undefined is exactly the same'); } if (x == undefined) { document.writeln('声明变量后默认值为undefined'); } if (x === undefined) { document.writeln('声明变量后默认值为exactly the same as undefined'); } if (x == null) { document.writeln('声明变量后默认值为null'); }

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    GEE,ISPRS,2020

    The ISPRS Journal of Photogrammetry and Remote Sensing (P&RS) is the official journal of the International Society for Photogrammetry and Remote Sensing (ISPRS). The Journal provides a channel of communication for scientists and professionals in all countries working in the many disciplines that employ photogrammetry, remote sensing, spatial information systems, computer vision, and related fields. The Journal is designed to serve as a source reference and archive of advancements in these disciplines. The P&RS objective is to publish high quality, peer-reviewed, preferably previously unpublished papers of a scientific/research, technological development or application/practical nature. P&RS will publish papers, including those based on ISPRS meeting presentations*, which are regarded as significant contributions in the above-mentioned fields. We especially encourage papers: of broad scientific interest; on innovative applications, particularly in new fields; of an interdisciplinary nature; on topics that have not been dealt with (or to a small degree) by P&RS or related journals; and on topics related to new possible scientific/professional directions. Preferably, theoretical papers should include applications, and papers dealing with systems and applications should include theoretical background. The scope of the journal is extensive and covers sensors, theory and algorithms, systems, experiments, developments and applications. Topics of interest include but are not limited to: Sensors: • Airborne and spaceborne multispectral and hyperspectral imaging systems • Airborne and terrestrial cameras • Airborne, terrestrial and mobile laser scanning • Range imaging • Active and passive imaging sensor characterisation • Sensor calibration and standardisation • Geosensor networks • Internet of Things Methods and procedures: • Spatial data handling technologies • Integrated sensor calibration and orientation • Surface and object reconstruction, modelling and interpretation • GIS data modelling, representation and structur

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