I need to extract all id values with casperjs

问题

id = casper.evaluate(function() { 
  return Array.prototype.map.call(document.querySelectorAll("image"), 
  function(e) {return e.getElementById();});});

this.echo(id);

回答1:

--Update--

If you want get elements containing a specific class just use a helper function to scrape the elements you are looking for.

Example:

var casper = require('casper').create();
var ids = [];

function getIdsByClassValue() {
  // use your selector here eg. '.image'.
  var elems = document.querySelectorAll('input[type="submit"]');
  return Array.prototype.map.call(elems, function (e) {
    // change to the attribute you are looking for.
    return e.getAttribute('value')
  });
}

casper.start('https://www.google.com/');

casper.then(function () {
  ids = this.evaluate(getIdsByClassValue);
});

casper.run(function() {
  this.echo('\n - ' + ids.join('\n - ')).exit();
});

You can use getElementsAttribute to do that.

.getElementsAttribute

Signature: getElementsAttribute(String selector, String attribute)

Retrieves the values of an attribute on each element matching the provided selector:

Here is an example.

var ids = [];

var casper = require('casper').create();

casper.start('https://google.com/', function() {
    this.wait(1000, function() {
        ids = this.getElementsAttribute('*', 'id')
          .filter(function(id) {
              return id.length > 0;
          })
    });
});

casper.then( function() {
  this.echo('\n - ' + ids.join('\n - ')).exit();
})

casper.run();

回答2:

return e.getElementById(); does obviously not make any sense, because getElementById is a function that expect one argument and is only available on the document.

It seems you want to return the id property:

var ids = casper.evaluate(function() { 
  return Array.prototype.map.call(document.querySelectorAll("image"), function(e) {
    return e.id;
  });
});

this.echo(ids);

来源：https://stackoverflow.com/questions/43932139/i-need-to-extract-all-id-values-with-casperjs

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javascript

casperjs